Delete doxygen.cfg, and use cwd-relative paths in doxygen.cfg.in.
Now "make doxygen" works for clang.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@131282 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/docs/Makefile b/docs/Makefile
index f82d820..2608046 100644
--- a/docs/Makefile
+++ b/docs/Makefile
@@ -16,10 +16,10 @@
 
 $(PROJ_OBJ_DIR)/doxygen.cfg: doxygen.cfg.in
 	cat $< | sed \
-	  -e 's/@abs_top_srcdir@/../g' \
+	  -e 's/@abs_srcdir@/./g' \
 	  -e 's/@DOT@/dot/g' \
 	  -e 's/@PACKAGE_VERSION@/mainline/' \
-	  -e 's/@abs_top_builddir@/../g' > $@
+	  -e 's/@abs_builddir@/./g' > $@
 endif
 
 include $(CLANG_LEVEL)/Makefile