Merge pull request #50 from facebook/iniline_strlen

Save 2ms at app startup by inlining strlen (from @swolchok)
diff --git a/fishhook.c b/fishhook.c
index 9c7d917..3f929c6 100644
--- a/fishhook.c
+++ b/fishhook.c
@@ -92,13 +92,12 @@
     }
     uint32_t strtab_offset = symtab[symtab_index].n_un.n_strx;
     char *symbol_name = strtab + strtab_offset;
-    if (strnlen(symbol_name, 2) < 2) {
-      continue;
-    }
+    bool symbol_name_longer_than_1 = symbol_name[0] && symbol_name[1];
     struct rebindings_entry *cur = rebindings;
     while (cur) {
       for (uint j = 0; j < cur->rebindings_nel; j++) {
-        if (strcmp(&symbol_name[1], cur->rebindings[j].name) == 0) {
+        if (symbol_name_longer_than_1 &&
+            strcmp(&symbol_name[1], cur->rebindings[j].name) == 0) {
           if (cur->rebindings[j].replaced != NULL &&
               indirect_symbol_bindings[i] != cur->rebindings[j].replacement) {
             *(cur->rebindings[j].replaced) = indirect_symbol_bindings[i];