Avoid putting generator.dwo in current working dir

At least some versions of GCC put the -gsplit-dwarf .dwo file in cwd when
compiling and linking is done together in one compiler invocation, see
<https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90575> "-gsplit-dwarf leaves
behind .dwo file in cwd".

Change-Id: I1b418e400a3e8107997fbbfd7f87ef3ac9fbbd28
Reviewed-on: https://gerrit.libreoffice.org/72841
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

compilerplugins/Makefile-clang.mk

@@ -198,7 +198,10 @@ $(CLANGOUTDIR)/sharedvisitor/generator$(CLANG_EXE_EXT): $(CLANGINDIR)/sharedvisi
 	$(call gb_Output_announce,$(subst $(BUILDDIR)/,,$@),$(true),GEN,1)
 	$(QUIET)$(COMPILER_PLUGINS_CXX) $(CLANGCXXFLAGS) $(CLANGWERROR) $(CLANGDEFS) $(CLANGTOOLDEFS) $(CLANGINCLUDES) \
         -DCLANGDIR=$(CLANGDIR) -DBUILDDIR=$(BUILDDIR) -I$(BUILDDIR)/config_host \
-        $< -o $@ -MMD -MT $@ -MP -MF $(CLANGOUTDIR)/sharedvisitor/generator.d $(CLANGTOOLLIBS)
+        -c $< -o $(CLANGOUTDIR)/sharedvisitor/generator.o -MMD -MT $@ -MP \
+        -MF $(CLANGOUTDIR)/sharedvisitor/generator.d
+	$(QUIET)$(COMPILER_PLUGINS_CXX) $(CLANGCXXFLAGS) $(CLANGOUTDIR)/sharedvisitor/generator.o \
+        -o $@ $(CLANGTOOLLIBS)
 
 $(CLANGOUTDIR)/sharedvisitor:
 	mkdir -p $(CLANGOUTDIR)/sharedvisitor