configure.ac: don't override LDFLAGS with CPPFLAGS

Don't override LDFLAGS with CPPFLAGS to avoid a build failure when
building statically with uclibc due to -static keyword being lost:

/home/buildroot/autobuild/run/instance-3/output-1/host/bin/xtensa-buildroot-linux-uclibc-gcc -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -o kismet_cap_linux_wifi ../interface_control.c.o ../wifi_ht_channels.c.o linux_wireless_control.c.o linux_netlink_control.c.o linux_nexmon_control.c.o linux_wireless_rfkill.c.o capture_linux_wifi.c.o ../libkismetdatasource.a -L/home/buildroot/autobuild/run/instance-3/output-1/host/bin/../xtensa-buildroot-linux-uclibc/sysroot/usr/lib -lpcap -L/home/buildroot/autobuild/run/instance-3/output-1/host/bin/../xtensa-buildroot-linux-uclibc/sysroot/home/buildroot/autobuild/run/instance-3/output-1/host/xtensa-buildroot-linux-uclibc/sysroot/usr/lib/.libs -lnl-genl-3 -lnl-3   -L/home/buildroot/autobuild/run/instance-3/output-1/host/bin/../xtensa-buildroot-linux-uclibc/sysroot/usr/lib -lpthread -lnl-genl-3 -lnl-3 -lpthread   -lpthread -L/home/buildroot/autobuild/run/instance-3/output-1/host/bin/../xtensa-buildroot-linux-uclibc/sysroot/usr/lib -lprotobuf-c  -lm
/home/buildroot/autobuild/run/instance-3/output-1/host/lib/gcc/xtensa-buildroot-linux-uclibc/9.3.0/../../../../xtensa-buildroot-linux-uclibc/bin/ld: /home/buildroot/autobuild/run/instance-3/output-1/host/lib/gcc/xtensa-buildroot-linux-uclibc/9.3.0/libgcc.a(unwind-dw2-fde-dip.o): in function `_Unwind_Find_registered_FDE':
/home/buildroot/autobuild/run/instance-3/output-1/build/host-gcc-final-9.3.0/build/xtensa-buildroot-linux-uclibc/libgcc/../../../libgcc/unwind-dw2-fde.c:1040: undefined reference to `dl_iterate_phdr'
collect2: error: ld returned 1 exit status

To fix this build failure, just drop OCPPFLAGS and OLDFLAGS which are
not used anymore

Fixes:
 - http://autobuild.buildroot.org/results/b859eb3850c0beb23e18010dc2f07cd0f5c14440

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>

configure.ac

@@ -619,11 +619,6 @@ else
     AC_MSG_RESULT([no])
 fi
 
-OCPPFLAGS=$CPPFLAGS
-CPPFLAGS="$CPPFLAGS"
-OLDFLAGS=$LDFLAGS
-LDFLAGS="$CPPFLAGS"
-
 # Do we need libm for math functions?
 AC_MSG_CHECKING([for libm math function in std libs])
 OCFL="$CFLAGS"