Add -imacros to C flags

[mbrunnen]

I am working in a project, that has some -imacros, using the Zephyr RTOS.
One problem was, that the compiler from the special toolchain was ignored, even though it is mentioned in the compile_commands.json file. I did fix it locally, with b:ale_c_cc_executable.The other problem is that the -imacros flag is ignored, hence this pull request.

Here is an extract from the compile_commands.json:

{
  "directory": "/home/mbrunnen/projects/embedded-system/applications/arbitrary-firmware/build",
  "command": "/home/mbrunnen/.local/opt/zephyr-sdk-0.11.4/arm-zephyr-eabi/bin/arm-zephyr-eabi-gcc \
    -DBUILD_VERSION=zephyr-v2.4.0-1136-gcf1bd1780417 \
    -DHSE_VALUE=8000000 \
    -DKERNEL \
    -DLV_CONF_INCLUDE_SIMPLE=1 \
    -DSTM32F103xB \
    -DUSE_FULL_LL_DRIVER \
    -DUSE_HAL_DRIVER \
    -D_FORTIFY_SOURCE=2 \
    -D__PROGRAM_START \
    -D__ZEPHYR__=1 \
    -I/home/mbrunnen/projects/embedded-system/system/zephyr/include \
    -Izephyr/include/generated \
    -I/home/mbrunnen/projects/embedded-system/system/zephyr/soc/arm/st_stm32/stm32f1 \
    -I/home/mbrunnen/projects/embedded-system/system/zephyr/drivers \
    -I/home/mbrunnen/projects/embedded-system/system/zephyr/soc/arm/st_stm32/common/. \
    -I/home/mbrunnen/projects/embedded-system/system/zephyr/soc/arm/st_stm32/common \
    -I/home/mbrunnen/projects/embedded-system/modules/hal/cmsis/CMSIS/Core/Include \
    -I/home/mbrunnen/projects/embedded-system/modules/hal/stm32/stm32cube/stm32f1xx/soc \
    -I/home/mbrunnen/projects/embedded-system/modules/hal/stm32/stm32cube/stm32f1xx/drivers/include \
    -I/home/mbrunnen/projects/embedded-system/modules/hal/stm32/stm32cube/stm32f1xx/drivers/include/Legacy \
    -I/home/mbrunnen/projects/embedded-system/system/zephyr/lib/gui/lvgl \
    -I/home/mbrunnen/projects/embedded-system/modules/lib/gui/lvgl \
    -isystem /home/mbrunnen/projects/embedded-system/system/zephyr/lib/libc/minimal/include \
    -isystem /home/mbrunnen/.local/opt/zephyr-sdk-0.11.4/arm-zephyr-eabi/bin/../lib/gcc/arm-zephyr-eabi/9.2.0/include \
    -isystem /home/mbrunnen/.local/opt/zephyr-sdk-0.11.4/arm-zephyr-eabi/bin/../lib/gcc/arm-zephyr-eabi/9.2.0/include-fixed    \
    -Os \
    -imacros /home/mbrunnen/projects/embedded-system/applications/arbitrary-firmware/build/zephyr/include/generated/autoconf.h \
    -ffreestanding \
    -fno-common \
    -g \
    -mcpu=cortex-m3 \
    -mthumb \
    -mabi=aapcs \
    -imacros /home/mbrunnen/projects/embedded-system/system/zephyr/include/toolchain/zephyr_stdint.h \
    -Wall \
    -Wformat \
    -Wformat-security \
    -Wno-format-zero-length \
    -Wno-main \
    -Wno-pointer-sign \
    -Wpointer-arith \
    -Wno-address-of-packed-member \
    -Wno-unused-but-set-variable \
    -Werror=implicit-int \
    -fno-asynchronous-unwind-tables \
    -fno-pie \
    -fno-pic \
    -fno-strict-overflow \
    -fno-reorder-functions \
    -fno-defer-pop \
    -fmacro-prefix-map=/home/mbrunnen/projects/embedded-system/applications/arbitrary-firmware=CMAKE_SOURCE_DIR \
    -fmacro-prefix-map=/home/mbrunnen/projects/embedded-system/system/zephyr=ZEPHYR_BASE \
    -fmacro-prefix-map=/home/mbrunnen/projects/embedded-system=WEST_TOPDIR \
    -ffunction-sections \
    -fdata-sections \
    -std=c99 \
    -nostdinc \
    -o CMakeFiles/app.dir/src/main.c.obj   \
    -c /home/mbrunnen/projects/embedded-system/applications/arbitrary-firmware/src/main.c",
  "file": "/home/mbrunnen/projects/embedded-system/applications/arbitrary-firmware/src/main.c"
}

[w0rp]

There's a test missing for this. If you search the codebase for the other switches here, there's one test that checks that the whitelisting of flags like these works. You should add some more text into that test and check that we permit the use of this flag too.

[stale]

This pull request has been automatically marked as stale because it has not been updated recently. Make sure to write tests and document your changes. See :help ale-dev for information on writing tests.
If your pull request is good to merge, bother w0rp or another maintainer again, and get them to merge it.

[mbrunnen]

There's a test missing for this. If you search the codebase for the other switches here, there's one test that checks that the whitelisting of flags like these works. You should add some more text into that test and check that we permit the use of this flag too.

Ok, I have added the tests.

[stale]

This pull request has been automatically marked as stale because it has not been updated recently. Make sure to write tests and document your changes. See :help ale-dev for information on writing tests.
If your pull request is good to merge, bother w0rp or another maintainer again, and get them to merge it.