RFR: JDK-8081692 Configure should verify that -fstack-protector is valid

[Magnus Ihse Bursie]

Not all versions of gcc support -fstack-protector. We should check that 
it is accepted as an argument before adding it to the flags.

Bug: https://bugs.openjdk.java.net/browse/JDK-8081692
WebRev inline:

diff --git a/common/autoconf/flags.m4 b/common/autoconf/flags.m4
--- a/common/autoconf/flags.m4
+++ b/common/autoconf/flags.m4
@@ -338,14 +338,16 @@
        # no adjustment
        ;;
      slowdebug )
-      # Add runtime stack smashing and undefined behavior checks
-      CFLAGS_DEBUG_OPTIONS="-fstack-protector-all --param 
ssp-buffer-size=1"
-      CXXFLAGS_DEBUG_OPTIONS="-fstack-protector-all --param 
ssp-buffer-size=1"
+      # Add runtime stack smashing and undefined behavior checks.
+      # Not all versions of gcc support -fstack-protector
+      STACK_PROTECTOR_CFLAG="-fstack-protector-all"
+      FLAGS_COMPILER_CHECK_ARGUMENTS([$STACK_PROTECTOR_CFLAG], [], 
[STACK_PROTECTOR_CFLAG=""])
+
+      CFLAGS_DEBUG_OPTIONS="$STACK_PROTECTOR_CFLAG --param 
ssp-buffer-size=1"
+      CXXFLAGS_DEBUG_OPTIONS="$STACK_PROTECTOR_CFLAG --param 
ssp-buffer-size=1"
        ;;
      esac
    fi
-  AC_SUBST(CFLAGS_DEBUG_OPTIONS)
-  AC_SUBST(CXXFLAGS_DEBUG_OPTIONS)

    # Optimization levels
    if test "x$TOOLCHAIN_TYPE" = xsolstudio; then

The AC_SUBST removal is just a bit of cleanup, we didn't use the 
*_DEBUG_OPTIONS in the spec files, just later on when constructing 
JDK_CFLAGS.

/Magnus