Makefile: Fix macOS cross-compilation

On macOS, the clang compiler is the default for C++ sources. Therefore, we also require the  to be set here as well. This updates the Makefile, but also fixes the check-gcc script, so that it understands we are cross compiling with the prefixed readelf binary.

Signed-off-by: Ella Fox <[email protected]>

Makefile

@@ -18,7 +18,7 @@ LD=$(CROSS_PREFIX)ld
 OBJCOPY=$(CROSS_PREFIX)objcopy
 OBJDUMP=$(CROSS_PREFIX)objdump
 STRIP=$(CROSS_PREFIX)strip
-CPP=cpp
+CPP=$(CROSS_PREFIX)cpp
 PYTHON=python3
 
 # Source files

scripts/check-gcc.sh

@@ -4,8 +4,8 @@
 f1="$1"
 f2="$2"
 
-s1=`readelf -A "$f1" | grep "Tag_ARM_ISA_use"`
-s2=`readelf -A "$f2" | grep "Tag_ARM_ISA_use"`
+s1=`${CROSS_PREFIX}readelf -A "$f1" | grep "Tag_ARM_ISA_use"`
+s2=`${CROSS_PREFIX}readelf -A "$f2" | grep "Tag_ARM_ISA_use"`
 
 if [ "$s1" != "$s2" ]; then
     echo ""