Add missing init section definitions

When adding __devinitconst etc. the __initconst variant
were missed.
Add this one and proper definitions for .head.text for use
in .S files.
The naming .head.text is preferred over .text.head as the
latter will conflict for a function named head when introducing
-ffunctions-sections.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

include/linux/init.h

@@ -42,6 +42,7 @@
    discard it in modules) */
 #define __init		__section(.init.text) __cold
 #define __initdata	__section(.init.data)
+#define __initconst	__section(.init.rodata)
 #define __exitdata	__section(.exit.data)
 #define __exit_call	__used __section(.exitcall.exit)
 
@@ -106,6 +107,7 @@
 #define __memexitconst   __section(.memexit.rodata)
 
 /* For assembly routines */
+#define __HEAD		.section	".head.text","ax"
 #define __INIT		.section	".init.text","ax"
 #define __FINIT		.previous