use -gsplit-dwarf also for compilerplugins if possible

~350MiB easily saved.

Change-Id: I9a91894cf4df7bc06d472795e564148fe8342995
Reviewed-on: https://gerrit.libreoffice.org/72588
Tested-by: Jenkins
Reviewed-by: Luboš Luňák <l.lunak@collabora.com>

compilerplugins/Makefile-clang.mk

@@ -73,6 +73,10 @@ ifdef LO_CLANG_SHARED_PLUGINS
 CLANGCXXFLAGS+=-DLO_CLANG_SHARED_PLUGINS
 endif
 
+ifeq ($(HAVE_GCC_SPLIT_DWARF),TRUE)
+CLANGCXXFLAGS+=-gsplit-dwarf
+endif
+
 QUIET=$(if $(verbose),,@)
 
 ifneq ($(ENABLE_WERROR),)