Don't use gnu++03 alias of gnu++98 for ODK builds

gnu++03 is just an alias for gnu++98 and was introduced in gcc 4.8.
This prevents older compilers from building the code.

Change-Id: I7e09338f26376c08c476561cdcddde39c7e62b09
Reviewed-on: https://gerrit.libreoffice.org/11501Reviewed-by: Stephan Bergmann <sbergman@redhat.com>
Tested-by: Stephan Bergmann <sbergman@redhat.com>

solenv/gbuild/platform/com_GCC_defs.mk

@@ -99,11 +99,10 @@ gb_CFLAGS_WERROR := $(if $(ENABLE_WERROR),-Werror)
 
 # This is the default in non-C++11 mode
 ifeq ($(COM_GCC_IS_CLANG),TRUE)
-# doesn't know gnu++03 and this seems to be the same anyway
 gb_CXX03FLAGS := -std=gnu++98 -Werror=c++11-extensions -Wno-c++11-long-long \
     -Wno-deprecated-declarations
 else
-gb_CXX03FLAGS := -std=gnu++03 -pedantic-errors -Wno-long-long \
+gb_CXX03FLAGS := -std=gnu++98 -pedantic-errors -Wno-long-long \
     -Wno-variadic-macros -Wno-non-virtual-dtor -Wno-deprecated-declarations
 endif