create-diff-object: Check ELF headers earlier

There is no point inspecting through the symbols of the ELF files
(original and patched) when the ELF headers do not meet requirements.

Check ELF headers as soon as the files are mapped.

Signed-off-by: Julien Thierry <jthierry@redhat.com>

kpatch-build/create-diff-object.c

@@ -3412,16 +3412,16 @@ int main(int argc, char *argv[])
 	kelf_base = kpatch_elf_open(orig_obj);
 	kelf_patched = kpatch_elf_open(patched_obj);
 
+	kpatch_compare_elf_headers(kelf_base->elf, kelf_patched->elf);
+	kpatch_check_program_headers(kelf_base->elf);
+	kpatch_check_program_headers(kelf_patched->elf);
+
 	kpatch_bundle_symbols(kelf_base);
 	kpatch_bundle_symbols(kelf_patched);
 
 	kpatch_detect_child_functions(kelf_base);
 	kpatch_detect_child_functions(kelf_patched);
 
-	kpatch_compare_elf_headers(kelf_base->elf, kelf_patched->elf);
-	kpatch_check_program_headers(kelf_base->elf);
-	kpatch_check_program_headers(kelf_patched->elf);
-
 	list_for_each_entry(sym, &kelf_base->symbols, list) {
 		if (sym->type == STT_FILE) {
 			hint = strdup(sym->name);