Fix CXXFLAGS for huge_val.m4.

Patch by Jeremy Huddleston!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153862 91177308-0d34-0410-b5e6-96231b3b80d8

autoconf/m4/huge_val.m4

@@ -6,7 +6,7 @@ AC_DEFUN([AC_HUGE_VAL_CHECK],[
   AC_CACHE_CHECK([for HUGE_VAL sanity], [ac_cv_huge_val_sanity],[
     AC_LANG_PUSH([C++])
     ac_save_CXXFLAGS=$CXXFLAGS
-    CXXFLAGS+=" -pedantic"
+    CXXFLAGS="$CXXFLAGS -pedantic"
     AC_RUN_IFELSE(
       AC_LANG_PROGRAM(
         [#include <math.h>],

configure

@@ -16371,7 +16371,7 @@ ac_link='$CXX -o conftest$ac_exeext $CXXFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ex
 ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
 
     ac_save_CXXFLAGS=$CXXFLAGS
-    CXXFLAGS+=" -pedantic"
+    CXXFLAGS="$CXXFLAGS -pedantic"
     if test "$cross_compiling" = yes; then
   ac_cv_huge_val_sanity=yes
 else