configure: add --extra-cxxflags option

same usage as --extra-cflags

Change-Id: Iff2ed7b8ebb6e51610ee0851aeec08413367ab23

build/make/configure.sh

@@ -73,6 +73,7 @@ Build options:
   --target=TARGET             target platform tuple [generic-gnu]
   --cpu=CPU                   optimize for a specific cpu rather than a family
   --extra-cflags=ECFLAGS      add ECFLAGS to CFLAGS [$CFLAGS]
+  --extra-cxxflags=ECXXFLAGS  add ECXXFLAGS to CXXFLAGS [$CXXFLAGS]
   ${toggle_extra_warnings}    emit harmless warnings (always non-fatal)
   ${toggle_werror}            treat warnings as errors, if possible
                               (not available with all compilers)
@@ -337,6 +338,10 @@ check_add_cflags() {
   check_cflags "$@" && add_cflags_only "$@"
 }
 
+check_add_cxxflags() {
+  check_cxxflags "$@" && add_cxxflags_only "$@"
+}
+
 check_add_asflags() {
   log add_asflags "$@"
   add_asflags "$@"
@@ -503,6 +508,9 @@ process_common_cmdline() {
       --extra-cflags=*)
         extra_cflags="${optval}"
         ;;
+      --extra-cxxflags=*)
+        extra_cxxflags="${optval}"
+        ;;
       --enable-?*|--disable-?*)
         eval `echo "$opt" | sed 's/--/action=/;s/-/ option=/;s/-/_/g'`
         if echo "${ARCH_EXT_LIST}" | grep "^ *$option\$" >/dev/null; then

configure

@@ -723,6 +723,10 @@ EOF
         check_add_cflags ${extra_cflags} || \
         die "Requested extra CFLAGS '${extra_cflags}' not supported by compiler"
     fi
+    if [ -n "${extra_cxxflags}" ]; then
+        check_add_cxxflags ${extra_cxxflags} || \
+        die "Requested extra CXXFLAGS '${extra_cxxflags}' not supported by compiler"
+    fi
 }