Remove src/Makefile.am.

* src/Makefile.am: Rename as...
	* src/local.mk: this.
	Prefix all the paths with src/.
	(AUTOMAKE_OPTIONS): Build object files in the sub dirs.
	(AM_CPPFLAGS): Find find in builddir/src.
	(YACC): Move the flags into...
	(AM_YFLAGS): here.
	* maint.mk (sc_tight_scope): Disable.
	It used to bounce to the version in src/Makefile.am which is now
	part of this very Makefile.
	* Makefile.am, configure.ac: Adjust.
	* src/scan-code-c.c, src/scan-code.l: We can no longer rely on
	include "..." to find files "here": we are no longer in src/, so
	qualify the includes with src/.
	* doc/Makefile.am (PREPATH): No longer include the top_builddir
	prefix.
	(.x.1): Adjust to be able to create src/foo from the top level
	Makefile, instead of going bounce to src/Makefile the creation of
	foo.

src/scan-gram.l

@@ -28,19 +28,19 @@
 #define gram_wrap() 1
 
 #define FLEX_PREFIX(Id) gram_ ## Id
-#include "flex-scanner.h"
+#include <src/flex-scanner.h>
 
-#include "complain.h"
-#include "files.h"
-#include "gram.h"
-#include "quotearg.h"
-#include "reader.h"
-#include "uniqstr.h"
+#include <src/complain.h>
+#include <src/files.h>
+#include <src/gram.h>
+#include <quotearg.h>
+#include <src/reader.h>
+#include <src/uniqstr.h>
 
 #include <mbswidth.h>
 #include <quote.h>
 
-#include "scan-gram.h"
+#include <src/scan-gram.h>
 
 #define YY_DECL GRAM_LEX_DECL