libpayload: Add an exec() and i386_do_exec() function

Add functions for libpayload to execute other payloads in memory,
and have those functions return cleanly.

Signed-off-by: Jordan Crouse <jordan.crouse@amd.com>
Acked-by: Uwe Hermann <uwe@hermann-uwe.de>


git-svn-id: svn://svn.coreboot.org/coreboot/trunk@3338 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1

payloads/libpayload/include/libpayload.h

@@ -145,6 +145,9 @@ void *malloc(size_t size);
 void *calloc(size_t nmemb, size_t size);
 void *realloc(void *ptr, size_t size);
 
+/* libc/exec.c */
+int exec(long addr, int argc, char **argv);
+
 /* libc/lib.c */
 int bcd2dec(int b);
 int dec2bcd(int d);