gbuild: revert to -O0 instead of -Og for GCC --enable-debug/dbgutil builds

Unfortunately -Og doesn't work as well as advertised, variables are
optimized away too often.

See thread at
https://lists.freedesktop.org/archives/libreoffice/2017-April/077479.html

Change-Id: I5fc141ea9c7c6931aaf8220c7abf6b413326049e

config_host.mk.in

@@ -242,7 +242,6 @@ export HAVE_GCC_FNO_ENFORCE_EH_SPECS=@HAVE_GCC_FNO_ENFORCE_EH_SPECS@
 export HAVE_GCC_FNO_INLINE=@HAVE_GCC_FNO_INLINE@
 export HAVE_GCC_FNO_SIZED_DEALLOCATION=@HAVE_GCC_FNO_SIZED_DEALLOCATION@
 export HAVE_GCC_GGDB2=@HAVE_GCC_GGDB2@
-export HAVE_GCC_OG=@HAVE_GCC_OG@
 export HAVE_GNUMAKE_FILE_FUNC=@HAVE_GNUMAKE_FILE_FUNC@
 export HAVE_LD_BSYMBOLIC_FUNCTIONS=@HAVE_LD_BSYMBOLIC_FUNCTIONS@
 export HAVE_LD_HASH_STYLE=@HAVE_LD_HASH_STYLE@

configure.ac

@@ -3750,7 +3750,6 @@ fi
 HAVE_GCC_GGDB2=
 HAVE_GCC_FINLINE_LIMIT=
 HAVE_GCC_FNO_INLINE=
-HAVE_GCC_OG=
 if test "$GCC" = "yes"; then
     AC_MSG_CHECKING([whether $CC supports -ggdb2])
     if test -n "$CLANGVER" -a 0"$CLANGVER" -le 30100; then
@@ -3801,22 +3800,6 @@ if test "$GCC" = "yes"; then
         AC_MSG_RESULT([no])
     fi
 
-    # clang as of version 4.0.0 (trunk 289424) doesn't do this very well (missing locals, bad param info in stack frame)
-    if test "$COM_IS_CLANG" != "TRUE"; then
-        AC_MSG_CHECKING([whether $CC supports -Og])
-        # Note that clang-3.1 reports a real error for this option
-        # so we do not need a special case for clang<=3.1 as above.
-        save_CFLAGS=$CFLAGS
-        CFLAGS="$CFLAGS -Werror -Og"
-        AC_LINK_IFELSE([AC_LANG_PROGRAM([[]], [[ return 0; ]])],[ HAVE_GCC_OG=TRUE ],[])
-        CFLAGS=$save_CFLAGS
-        if test "$HAVE_GCC_OG" = "TRUE"; then
-            AC_MSG_RESULT([yes])
-        else
-            AC_MSG_RESULT([no])
-        fi
-    fi
-
     if test "$host_cpu" = "m68k"; then
         AC_MSG_CHECKING([whether $CC supports -mlong-jump-table-offsets])
         save_CFLAGS=$CFLAGS
@@ -3833,7 +3816,6 @@ fi
 AC_SUBST(HAVE_GCC_GGDB2)
 AC_SUBST(HAVE_GCC_FINLINE_LIMIT)
 AC_SUBST(HAVE_GCC_FNO_INLINE)
-AC_SUBST(HAVE_GCC_OG)
 
 dnl ===================================================================
 dnl  Test the gcc version

solenv/gbuild/platform/com_GCC_defs.mk

@@ -186,9 +186,7 @@ ifeq ($(HAVE_GCC_FNO_DEFAULT_INLINE),TRUE)
 FNO_DEFAULT_INLINE=-fno-default-inline
 endif
 
-# note: this overrides -O0 from the gb_COMPILERNOOPTFLAGS with -Og if
-# available, so that the former remains no-optimization for when that is needed
-gb_DEBUG_CFLAGS := $(if $(HAVE_GCC_OG),-Og) $(FINLINE_LIMIT0) $(FNO_INLINE)
+gb_DEBUG_CFLAGS := $(FINLINE_LIMIT0) $(FNO_INLINE)
 gb_DEBUG_CXXFLAGS := $(FNO_DEFAULT_INLINE)