objtool: Move objtool_file struct off the stack

Objtool uses over 512k of stack, thanks to the hash table embedded in
the objtool_file struct. This causes an unnecessarily large stack
allocation and breaks users with low stack limits.

Move the struct off the stack.

Fixes: 042ba73fe7eb ("objtool: Add several performance improvements")
Reported-by: Vassili Karpov <[e-mail]>
Signed-off-by: Josh Poimboeuf <[e-mail]>
Signed-off-by: Thomas Gleixner <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: [e-mail]
Link: https://lkml.kernel.org/r/[e-mail]

tools/objtool/check.c

···
 	elf_close(file->elf);
 }
 
+static struct objtool_file file;
+
 int check(const char *_objname, bool orc)
 {
-	struct objtool_file file;
 	int ret, warnings = 0;
 
 	objname = _objname;