libpayload: Add commonlib/bsd include path to lpgcc

coreinfo and nvramcui are using libpayload/bin/lpgcc and libpayload
build directory as a base, instead of installing it first. This caused
include errors, because commonlib/bsd is not present there. This patch
introduces comonlib/bsd include path to lpgcc CFLAGS if it is being
built using libpayload build directory as a base.

Change-Id: I7d1fe9e5dc3e7c1c1ba825a1bf19972722b42778
Signed-off-by: Jakub Czapiga <jacz@semihalf.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/60171
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>

payloads/libpayload/bin/lpgcc

@@ -167,6 +167,8 @@ if [ $_LIBDIR = $_OBJ ]; then
     if [ "$CONFIG_LP_TINYCURSES" = y ]; then
 	_CFLAGS="$_CFLAGS -I$BASE/../curses"
     fi
+
+    _CFLAGS="$_CFLAGS -I$BASE/../../../src/commonlib/bsd/include"
 fi
 
 # Check for the -fno-stack-protector silliness