ld.so: Add architecture specific fields

To support Intel Control-flow Enforcement Technology (CET) run-time
control:

1. An architecture specific field in the writable ld.so namespace is
needed to indicate if CET features are enabled at run-time.
2. An architecture specific field in struct link_map is needed if
CET features are enabled in an ELF module.

This patch adds dl-procruntime.c to the writable ld.so namespace and
link_map.h to struct link_map.

Tested with build-many-glibcs.py.

	* elf/dl-support.c: Include <dl-procruntime.c>.
	* include/link.h: Include <link_map.h>.
	* sysdeps/generic/dl-procruntime.c: New file.
	* sysdeps/generic/link_map.h: Likewise.
	* sysdeps/generic/ldsodefs.h: Include <dl-procruntime.c> in
	the writable ld.so namespace.

sysdeps/generic/dl-procruntime.c

@@ -0,0 +1 @@
+/* No architecture specific definitions.  */

sysdeps/generic/ldsodefs.h

@@ -373,6 +373,13 @@ struct rtld_global
   EXTERN void (*_dl_rtld_unlock_recursive) (void *);
 #endif
 
+  /* Get architecture specific definitions.  */
+#define PROCINFO_DECL
+#ifndef PROCINFO_CLASS
+# define PROCINFO_CLASS EXTERN
+#endif
+#include <dl-procruntime.c>
+
   /* If loading a shared object requires that we make the stack executable
      when it was not, we do it by calling this function.
      It returns an errno code or zero on success.  */
@@ -529,10 +536,6 @@ struct rtld_global_ro
 #endif
 
   /* Get architecture specific definitions.  */
-#define PROCINFO_DECL
-#ifndef PROCINFO_CLASS
-# define PROCINFO_CLASS EXTERN
-#endif
 #include <dl-procinfo.c>
 
   /* Names of shared object for which the RPATH should be ignored.  */

sysdeps/generic/link_map.h

@@ -0,0 +1 @@
+/* No architecture specific definitions.  */