Makefile does not account for older toolchains

[technotive]

Edits; Markdown fix.

In the process of trying to get the standard benchmarks to work according to the readme. At this point I am at the "Running tests and benchmarks" part of the readme.
Linuxmint 17.3 (Rosa) with GCC/G++ 5.5 has the following output when calling make:

make -C crypto_kem/frodo640-cshake/opt libpqm4.a
make[1]: Entering directory '/home/nevy/Research/pqm4/crypto_kem/frodo640-cshake/opt'
arm-none-eabi-gcc -I/home/nevy/Research/pqm4/common -Wall -Wextra -O3 -mthumb -mcpu=cortex-m4 -mfloat-abi=hard -mfpu=fpv4-sp-d16 -c -o frodo640.o frodo640.c
In file included from frodo640.c:30:0:
kem.c: In function 'crypto_kem_dec':
kem.c:129:5: error: 'for' loop initial declarations are only allowed in C99 mode
     for (int i = 0; i < PARAMS_N*PARAMS_NBAR; i++) BBp[i] = BBp[i] & ((1 << PARAMS_LOGQ)-1);
     ^
kem.c:129:5: note: use option -std=c99 or -std=gnu99 to compile your code
In file included from frodo640.c:32:0:
frodo_macrify.c: In function 'frodo_add':
frodo_macrify.c:222:5: error: 'for' loop initial declarations are only allowed in C99 mode
     for (int i = 0; i < (PARAMS_NBAR*PARAMS_NBAR); i++) {
     ^
frodo_macrify.c: In function 'frodo_sub':
frodo_macrify.c:233:5: error: 'for' loop initial declarations are only allowed in C99 mode
     for (int i = 0; i < (PARAMS_NBAR*PARAMS_NBAR); i++) {
     ^
make[1]: *** [frodo640.o] Error 1
make[1]: Leaving directory '/home/nevy/Research/pqm4/crypto_kem/frodo640-cshake/opt'
make: *** [crypto_kem/frodo640-cshake/opt] Error 2

Which is supposedly remedied by:
make CFLAGS="-std=gnu99"
Which results in:

...
newhope_asm.S:734: Error: attempt to use an ARM instruction on a Thumb-only processor -- 'pop {r0-r12,pc}'
make[1]: *** [newhope_asm.o] Error 1
rm kem.o cpapke.o
make[1]: Leaving directory '/home/nevy/Research/pqm4/crypto_kem/newhope1024cca/m4'
make: *** [crypto_kem/newhope1024cca/m4] Error 2

On the first run.

Then we run make again, and then make CFLAGS="-std=gnu99" again to get

...
make[1]: Leaving directory '/home/nevy/Research/pqm4/crypto_sign/sphincs-shake256-128s/ref'
make -C crypto_sign/sphincs-shake256-128s/ref libpqhost.a
make[1]: Entering directory '/home/nevy/Research/pqm4/crypto_sign/sphincs-shake256-128s/ref'
gcc -I/home/nevy/Research/pqm4/common -Wall -Wextra -O3 -c -o hash_shake256_host.o hash_shake256.c
gcc -I/home/nevy/Research/pqm4/common -Wall -Wextra -O3 -c -o hash_address_host.o hash_address.c
gcc -I/home/nevy/Research/pqm4/common -Wall -Wextra -O3 -c -o wots_host.o wots.c
gcc -I/home/nevy/Research/pqm4/common -Wall -Wextra -O3 -c -o utils_host.o utils.c
gcc -I/home/nevy/Research/pqm4/common -Wall -Wextra -O3 -c -o fors_host.o fors.c
gcc -I/home/nevy/Research/pqm4/common -Wall -Wextra -O3 -c -o sign_host.o sign.c
gcc-ar rcs libpqhost.a hash_shake256_host.o hash_address_host.o wots_host.o utils_host.o fors_host.o sign_host.o
make[1]: Leaving directory '/home/nevy/Research/pqm4/crypto_sign/sphincs-shake256-128s/ref'
mkdir -p obj 
arm-none-eabi-gcc -std=gnu99 -o obj/stm32f4_wrapper.o -c common/stm32f4_wrapper.c
In file included from common/stm32f4_wrapper.c:1:0:
common/stm32wrapper.h:4:34: fatal error: libopencm3/stm32/rcc.h: No such file or directory
 #include <libopencm3/stm32/rcc.h>
                                  ^
compilation terminated.
make: *** [obj/stm32f4_wrapper.o] Error 1

After which a regular make results in:

...
arm-none-eabi-gcc -O3 -Wall -Wextra -Wimplicit-function-declaration -Wredundant-decls -Wmissing-prototypes -Wstrict-prototypes -Wundef -Wshadow -I./libopencm3/include -fno-common -mthumb -mcpu=cortex-m4 -mfloat-abi=hard -mfpu=fpv4-sp-d16 -std=gnu99 -MD -DSTM32F4 -std=gnu99 -o obj/stm32f4_wrapper.o -c common/stm32f4_wrapper.c
In file included from ./libopencm3/include/libopencm3/cm3/nvic.h:133:0,
                 from common/stm32wrapper.h:7,
                 from common/stm32f4_wrapper.c:1:
./libopencm3/include/libopencm3/dispatch/nvic.h:14:39: fatal error: libopencm3/stm32/f4/nvic.h: No such file or directory
 # include <libopencm3/stm32/f4/nvic.h>
                                       ^
compilation terminated.
make: *** [obj/stm32f4_wrapper.o] Error 1

At which point alternating both method does not change anything anymore.

Calling make clean will revert the situation to the way it was at the beginning of this message.

Note that I originally updated from GCC 4.8 (Which showed similar behaviour) to GCC 5.5 because I read that gnu11 is the new default for GCC 5.5, which would make messing with the CFLAG unessecary. Sadly, GCC 5.5 did not deliver what I thought it would.

It looks like some libraries need the "-std=gnu99" flag but somehow either something else gets misconfigured because of it, or it was misconfigured from the start. Can someone help me debug this? I am not an expert when it comes to Makefiles, so it might as well be I just forgot something.

[technotive]

Additional information:
Adjusting Frodo to be compliant with c89/gnu89 by moving variable declarations out of for-loops results in the following error when calling make:

arm-none-eabi-gcc -O3 -Wall -Wextra -Wimplicit-function-declaration -Wredundant-decls -Wmissing-prototypes -Wstrict-prototypes -Wundef -Wshadow -I./libopencm3/include -fno-common -mthumb -mcpu=cortex-m4 -mfloat-abi=hard -mfpu=fpv4-sp-d16 -std=gnu99 -MD -DSTM32F4 -std=gnu99 -o obj/stm32f4_wrapper.o -c common/stm32f4_wrapper.c
In file included from ./libopencm3/include/libopencm3/cm3/nvic.h:133:0,
                 from common/stm32wrapper.h:7,
                 from common/stm32f4_wrapper.c:1:
./libopencm3/include/libopencm3/dispatch/nvic.h:14:39: fatal error: libopencm3/stm32/f4/nvic.h: No such file or directory
 # include <libopencm3/stm32/f4/nvic.h>
                                       ^
compilation terminated.
make: *** [obj/stm32f4_wrapper.o] Error 1

[technotive]

independently first calling make for libopencm3 solved the issue in combination with making Frodo c89/gnu89 compliant.