[easytag] Use CXXFLAGS from environment

[David King <davidk src gnome org>]

commit 5a73d051b844e8c8e01f0f8d51e8839e4de3bf1a
Author: David King <amigadave amigadave com>
Date:   Sat Apr 12 13:14:38 2014 +0100

    Use CXXFLAGS from environment
    
    Fix a typo when checking for warning options to pass to the C++
    compiler, and ensure that CXXFLAGS set in the environment are passed to
    the compiler.

 configure.ac |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index ae11d83..eacea67 100644
--- a/configure.ac
+++ b/configure.ac
@@ -344,9 +344,9 @@ CFLAGS="$realsave_CFLAGS"
 AC_SUBST([WARN_CFLAGS], ["$tested_warning_flags"])
 AC_LANG_PUSH([C++])
 
-realsave_CFLAGS="$CXXFLAGS"
+realsave_CXXFLAGS="$CXXFLAGS"
 for option in $warning_flags; do
-    save_CFLAGS="$CXXFLAGS"
+    save_CXXFLAGS="$CXXFLAGS"
     CXXFLAGS="$CXXFLAGS -Werror $option"
        AC_MSG_CHECKING([whether the c++ compiler understands $option])
        AC_COMPILE_IFELSE([AC_LANG_PROGRAM], [has_option=yes], [has_option=no])
@@ -355,7 +355,7 @@ for option in $warning_flags; do
        AS_IF([test $has_option = yes],
              [tested_cxx_warning_flags="$tested_cxx_warning_flags $option"])
        unset has_option
-       unset save_CFLAGS
+       unset save_CXXFLAGS
 done
 unset option
 CXXFLAGS="$realsave_CXXFLAGS"