kbuild: move scripts/basic/docproc.c to scripts/docproc.c

Move docproc from scripts/basic to scripts so it is only built for *doc
targets instead of every time the kernel is built.
diff --git a/scripts/basic/Makefile b/scripts/basic/Makefile
index 4c324a1..4fcef87 100644
--- a/scripts/basic/Makefile
+++ b/scripts/basic/Makefile
@@ -7,9 +7,8 @@
 # .config is included by main Makefile.
 # ---------------------------------------------------------------------------
 # fixdep: 	 Used to generate dependency information during build process
-# docproc:	 Used in Documentation/DocBook
 
-hostprogs-y	:= fixdep docproc
+hostprogs-y	:= fixdep
 always		:= $(hostprogs-y)
 
 # fixdep is needed to compile other host programs