x86, perf probe: Fix warning in test_get_len()

Fix the following warning:

 arch/x86/tools/test_get_len.c: In function "main":
 arch/x86/tools/test_get_len.c:116: warning: unused variable "c"
Signed-off-by: NJean Delvare <khali@linux-fr.org>
Cc: Masami Hiramatsu <mhiramat@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

arch/x86/tools/test_get_len.c

@@ -113,7 +113,7 @@ int main(int argc, char **argv)
 	char line[BUFSIZE], sym[BUFSIZE] = "<unknown>";
 	unsigned char insn_buf[16];
 	struct insn insn;
-	int insns = 0, c;
+	int insns = 0;
 	int warnings = 0;
 
 	parse_args(argc, argv);