kbuild: prevent modpost from looking for a .cmd file for a static library linked into a module

This fixes a compile time warning which occurs whenever a static library
is linked into a kernel module. MODPOST tries to look for a
".<modulename>.cmd" file to look for its dependencies, but that file
doesn't exist or get generated for static libraries.

This patch prevents modpost from looking for a .cmd file when a module is
linked with a static library

[[e-mail]: coding-style fixes]
Signed-off-by: Ashutosh Naik <[e-mail]>
Cc: Rusty Russell <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Sam Ravnborg <[e-mail]>

scripts/mod/sumversion.c

···
 	release_file(file, len);
 	return 1;
 }
+/* Check whether the file is a static library or not */
+static int is_static_library(const char *objfile)
+{
+	int len = strlen(objfile);
+	if (objfile[len - 2] == '.' && objfile[len - 1] == 'a')
+		return 1;
+	else
+		return 0;
+}
 
 /* We have dir/file.o.  Open dir/.file.o.cmd, look for deps_ line to
  * figure out source file. */
···
 	while ((fname = strsep(&sources, " ")) != NULL) {
 		if (!*fname)
 			continue;
-		if (!parse_source_files(fname, &md))
+		if (!(is_static_library(fname)) &&
+				!parse_source_files(fname, &md))
 			goto release;
 	}