x86_64: fix headers_install

A bug in headers_install for ARCH=x86_64 yields an asm/ directory full of
files all of which are using the same #ifdef guard, "__ASM_STUB_" with no
postfix.  So the second and later asm files #included in the same C file
(often through standard headers like ioctl.h) yields no symbols.

Strangeness with the Ubuntu 'tell me if I support something that's not
explcitly mentioned in POSIX, and I'll strip it out' shell, I believe.

We don't need the 'export' but we do need a semicolon at the end of the
FNAME line:
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Rob Landley <rob@landley.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

scripts/Makefile.headersinst

@@ -108,7 +108,7 @@ quiet_cmd_mkdir		  = MKDIR   $(patsubst $(INSTALL_HDR_PATH)/%,%,$@)
 
 quiet_cmd_gen		  = GEN     $(patsubst $(INSTALL_HDR_PATH)/%,%,$@)
       cmd_gen		  = \
-FNAME=$(patsubst $(INSTALL_HDR_PATH)/$(_dst)/%,%,$@)			\
+FNAME=$(patsubst $(INSTALL_HDR_PATH)/$(_dst)/%,%,$@);			\
 STUBDEF=__ASM_STUB_`echo $$FNAME | tr a-z.- A-Z__`;			\
 (echo "/* File autogenerated by 'make headers_install' */" ;		\
 echo "\#ifndef $$STUBDEF" ;						\