add ABI symbols for strtol family functions

these odd names are actually generated by mess in glibc's stdlib.h, so
any glibc-linked program using strtol needs them to run against musl.

src/stdlib/strtol.c

@@ -4,6 +4,7 @@
 #include <inttypes.h>
 #include <limits.h>
 #include <ctype.h>
+#include "libc.h"
 
 static unsigned long long strtox(const char *s, char **p, int base, unsigned long long lim)
 {
@@ -54,3 +55,10 @@ uintmax_t strtoumax(const char *restrict s, char **restrict p, int base)
 {
 	return strtoull(s, p, base);
 }
+
+weak_alias(strtol, __strtol_internal);
+weak_alias(strtoul, __strtoul_internal);
+weak_alias(strtoll, __strtoll_internal);
+weak_alias(strtoull, __strtoull_internal);
+weak_alias(strtoimax, __strtoimax_internal);
+weak_alias(strtoumax, __strtoumax_internal);