It is building the generator exe that depends on $(CLANGOUTDIR)/sharedvisitor

...or else

  -MF $(CLANGOUTDIR)/sharedvisitor/generator.d

in the command line for building the generator exe could produce a failure
because the dir does not exist yet.  (The dependency of compilerplugins-build on
$(CLANGOUTDIR)/sharedvisitor had been added with
adb08e89 "make (some) clang plugins share the
same RecursiveASTVisitor" for reasons that are not clear to me.)

Change-Id: I124b95be5e8ba36dc5d7502208c61ccf045516f5
Reviewed-on: https://gerrit.libreoffice.org/69307
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

compilerplugins/Makefile-clang.mk

@@ -183,14 +183,13 @@ CLANGTOOLLIBS = -lclangTooling -lclangDriver -lclangFrontend -lclangParse -lclan
 # Path to the clang system headers (no idea if there's a better way to get it).
 CLANGTOOLDEFS = -DCLANGSYSINCLUDE=$(shell $(LLVMCONFIG) --libdir)/clang/$(shell $(LLVMCONFIG) --version | sed 's/svn//')/include
 
-$(CLANGOUTDIR)/sharedvisitor/generator$(CLANG_EXE_EXT): $(CLANGINDIR)/sharedvisitor/generator.cxx
+$(CLANGOUTDIR)/sharedvisitor/generator$(CLANG_EXE_EXT): $(CLANGINDIR)/sharedvisitor/generator.cxx \
+        | $(CLANGOUTDIR)/sharedvisitor
 	$(call gb_Output_announce,$(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)
 
-compilerplugins-build: $(CLANGOUTDIR)/sharedvisitor
-
 $(CLANGOUTDIR)/sharedvisitor:
 	mkdir -p $(CLANGOUTDIR)/sharedvisitor