Bug 1613799 - Stop supporting manifests in the objdir. r=froydnj

Baby steps. Working towards not using $(MT), let's unsupport what we
currently don't rely on (and in case someone would try to rely on it,
throw an error).

Differential Revision: https://phabricator.services.mozilla.com/D61948

config/rules.mk

@@ -465,13 +465,8 @@ ifeq (_WINNT,$(GNU_CC)_$(OS_ARCH))
 	$(LINKER) -NOLOGO -OUT:$@ -PDB:$(LINK_PDBFILE) -IMPLIB:$(basename $(@F)).lib $(WIN32_EXE_LDFLAGS) $(LDFLAGS) $(MOZ_PROGRAM_LDFLAGS) $($(notdir $@)_OBJS) $(RESFILE) $(STATIC_LIBS) $(SHARED_LIBS) $(OS_LIBS)
 ifdef MSMANIFEST_TOOL
 	@if test -f $@.manifest; then \
-		if test -f '$(srcdir)/$(notdir $@).manifest'; then \
-			echo 'Embedding manifest from $(srcdir_rel)/$(notdir $@).manifest and $@.manifest'; \
-			$(MT) -NOLOGO -MANIFEST '$(srcdir_rel)/$(notdir $@).manifest' $@.manifest -OUTPUTRESOURCE:$@\;1; \
-		else \
-			echo 'Embedding manifest from $@.manifest'; \
-			$(MT) -NOLOGO -MANIFEST $@.manifest -OUTPUTRESOURCE:$@\;1; \
-		fi; \
+		echo "Manifest in objdir is not supported"; \
+		exit 1; \
 	elif test -f '$(srcdir)/$(notdir $@).manifest'; then \
 		echo 'Embedding manifest from $(srcdir_rel)/$(notdir $@).manifest'; \
 		$(MT) -NOLOGO -MANIFEST '$(srcdir_rel)/$(notdir $@).manifest' -OUTPUTRESOURCE:$@\;1; \
@@ -495,13 +490,8 @@ ifeq (_WINNT,$(GNU_CC)_$(HOST_OS_ARCH))
 	$(HOST_LINKER) -NOLOGO -OUT:$@ -PDB:$(HOST_PDBFILE) $($(notdir $@)_OBJS) $(WIN32_EXE_LDFLAGS) $(HOST_LDFLAGS) $(HOST_LINKER_LIBPATHS) $(HOST_LIBS) $(HOST_EXTRA_LIBS)
 ifdef MSMANIFEST_TOOL
 	@if test -f $@.manifest; then \
-		if test -f '$(srcdir)/$(notdir $@).manifest'; then \
-			echo 'Embedding manifest from $(srcdir_rel)/$(notdir $@).manifest and $@.manifest'; \
-			$(MT) -NOLOGO -MANIFEST '$(srcdir_rel)/$(notdir $@).manifest' $@.manifest -OUTPUTRESOURCE:$@\;1; \
-		else \
-			echo 'Embedding manifest from $@.manifest'; \
-			$(MT) -NOLOGO -MANIFEST $@.manifest -OUTPUTRESOURCE:$@\;1; \
-		fi; \
+		echo "Manifest in objdir is not supported"; \
+		exit 1; \
 	elif test -f '$(srcdir)/$(notdir $@).manifest'; then \
 		echo 'Embedding manifest from $(srcdir_rel)/$(notdir $@).manifest'; \
 		$(MT) -NOLOGO -MANIFEST '$(srcdir_rel)/$(notdir $@).manifest' -OUTPUTRESOURCE:$@\;1; \
@@ -624,13 +614,8 @@ ifeq (_WINNT,$(GNU_CC)_$(OS_ARCH))
 ifdef MSMANIFEST_TOOL
 ifdef EMBED_MANIFEST_AT
 	@if test -f $@.manifest; then \
-		if test -f '$(srcdir)/$@.manifest'; then \
-			echo 'Embedding manifest from $(srcdir_rel)/$@.manifest and $@.manifest'; \
-			$(MT) -NOLOGO -MANIFEST '$(srcdir_rel)/$@.manifest' $@.manifest -OUTPUTRESOURCE:$@\;$(EMBED_MANIFEST_AT); \
-		else \
-			echo 'Embedding manifest from $@.manifest'; \
-			$(MT) -NOLOGO -MANIFEST $@.manifest -OUTPUTRESOURCE:$@\;$(EMBED_MANIFEST_AT); \
-		fi; \
+		echo "Manifest in objdir is not supported"; \
+		exit 1; \
 	elif test -f '$(srcdir)/$@.manifest'; then \
 		echo 'Embedding manifest from $(srcdir_rel)/$@.manifest'; \
 		$(MT) -NOLOGO -MANIFEST '$(srcdir_rel)/$@.manifest' -OUTPUTRESOURCE:$@\;$(EMBED_MANIFEST_AT); \