Makefile: Fix "make cscope TAGS"

Cscope and TAGS files work in source directory rather than the build
directory, also, don't ask users to run configure first, because they
may have an out of tree build.
Signed-off-by: NFam Zheng <famz@redhat.com>
Reviewed-by: NJohn Snow <jsnow@redhat.com>
Signed-off-by: NMichael Tokarev <mjt@tls.msk.ru>

Makefile

@@ -3,6 +3,11 @@
 # Always point to the root of the build tree (needs GNU make).
 BUILD_DIR=$(CURDIR)
 
+# Before including a proper config-host.mak, assume we are in the source tree
+SRC_PATH=.
+
+UNCHECKED_GOALS := %clean TAGS cscope
+
 # All following code might depend on configuration variables
 ifneq ($(wildcard config-host.mak),)
 # Put the all: rule here so that config-host.mak can contain dependencies.
@@ -38,7 +43,7 @@ config-host.mak: $(SRC_PATH)/configure
 	fi
 else
 config-host.mak:
-ifneq ($(filter-out %clean,$(MAKECMDGOALS)),$(if $(MAKECMDGOALS),,fail))
+ifneq ($(filter-out $(UNCHECKED_GOALS),$(MAKECMDGOALS)),$(if $(MAKECMDGOALS),,fail))
 	@echo "Please call configure before running make!"
 	@exit 1
 endif
@@ -455,9 +460,9 @@ TAGS:
 	find "$(SRC_PATH)" -name '*.[hc]' -exec etags --append {} +
 
 cscope:
-	rm -f ./cscope.*
-	find "$(SRC_PATH)" -name "*.[chsS]" -print | sed 's,^\./,,' > ./cscope.files
-	cscope -b
+	rm -f "$(SRC_PATH)"/cscope.*
+	find "$(SRC_PATH)/" -name "*.[chsS]" -print | sed 's,^\./,,' > "$(SRC_PATH)/cscope.files"
+	cscope -b -i"$(SRC_PATH)/cscope.files"
 
 # opengl shader programs
 ui/shader/%-vert.h: $(SRC_PATH)/ui/shader/%.vert $(SRC_PATH)/scripts/shaderinclude.pl
@@ -600,7 +605,7 @@ endif # CONFIG_WIN
 
 # Add a dependency on the generated files, so that they are always
 # rebuilt before other object files
-ifneq ($(filter-out %clean,$(MAKECMDGOALS)),$(if $(MAKECMDGOALS),,fail))
+ifneq ($(filter-out $(UNCHECKED_GOALS),$(MAKECMDGOALS)),$(if $(MAKECMDGOALS),,fail))
 Makefile: $(GENERATED_HEADERS)
 endif