feat: export CGO_{C,CPP,CXX,LD}FLAGS from un-prefixed counterparts

Author: CSharperMantle

proc/12-arch-flags.sh

@@ -87,6 +87,14 @@ ab_arch_setflags() {
         declare -n _tmp="_${flagtype}"
         export "${flagtype}"="${_tmp[*]}"
         abdbg "${flagtype}=${_tmp[*]}"
+        # export CGO counterparts for CFLAGS, CXXFLAGS, and LDFLAGS.
+        # see <https://go.dev/src/cmd/cgo/doc.go>.
+        case "${flagtype}" in
+            CFLAGS|CXXFLAGS|LDFLAGS)
+            export "CGO_${flagtype}"="${_tmp[*]}"
+            abdbg "CGO_${flagtype}=${_tmp[*]}"
+            ;;
+        esac
 
     # Do the same thing if HWCAPS is enabled
     if bool "$hwcaps_active" ; then