Add remaining _l function stubs.

Bug: http://b/65595804
Test: ran tests
Change-Id: I3bea3af20b354d1f0d3e05fd35421a9045f29020
diff --git a/libc/tzcode/strptime.c b/libc/tzcode/strptime.c
index 0567aa4..2100630 100644
--- a/libc/tzcode/strptime.c
+++ b/libc/tzcode/strptime.c
@@ -430,3 +430,7 @@
     *dest = result;
     return (1);
 }
+
+char* strptime_l(const char* buf, const char* fmt, struct tm* tm, locale_t l) {
+  return strptime(buf, fmt, tm);
+}