Makefile: Minor cscope fixups

Create cscope symbols for assembly files in addition to .c/.h files.
Create cscope database with full path instead of relative path so cscope
can be used with CSCOPE_DB in any directory.
Signed-off-by: NAlexandre Raymond <cerbere@gmail.com>
Signed-off-by: NStefan Hajnoczi <stefanha@linux.vnet.ibm.com>

Makefile

@@ -291,7 +291,7 @@ TAGS:
 
 cscope:
 	rm -f ./cscope.*
-	find . -name "*.[ch]" -print | sed 's,^\./,,' > ./cscope.files
+	find "$(SRC_PATH)" -name "*.[chsS]" -print | sed 's,^\./,,' > ./cscope.files
 	cscope -b
 
 # documentation