[master] portability fix and unset werror_ok fix

This is for ticket 2945.
Don't use grep -q (not portable).
Also use quotes around "$werror_ok" just in test just in case is unset.

No changelog message as it appears it worked before but was just noisy.

configure.ac

@@ -76,7 +76,7 @@ AM_CONDITIONAL(USE_CLANGPP, test "X${CLANGPP}" = "Xyes")
 
 dnl Determine if weare using GNU sed
 GNU_SED=no
-$SED --version 2> /dev/null | grep -q GNU
+$SED --version 2> /dev/null | grep GNU > /dev/null 2>&1
 if test $? -eq 0; then
   GNU_SED=yes
 fi
@@ -445,7 +445,7 @@ fi
 # Python 3.2 has an unused parameter in one of its headers. This
 # has been reported, but not fixed as of yet, so we check if we need
 # to set -Wno-unused-parameter.
-if test "X$GXX" = "Xyes" -a $werror_ok = 1; then
+if test "X$GXX" = "Xyes" -a "$werror_ok" = 1; then
 	CPPFLAGS_SAVED="$CPPFLAGS"
 	CPPFLAGS=${PYTHON_INCLUDES}
 	CXXFLAGS_SAVED="$CXXFLAGS"