PATCH: [perl #132750] Silence uninit warning

I inspected the code, and there is no problem here; it's a compiler
mistake.  Nevertheless, smply initializing the variable silences it.

Author: khwilliamson

doop.c

@@ -1018,7 +1018,7 @@ Perl_do_vop(pTHX_ I32 optype, SV *sv, SV *left, SV *right)
     STRLEN rightlen;
     const char *lc;
     const char *rc;
-    STRLEN len;
+    STRLEN len = 0;
     STRLEN lensave;
     const char *lsave;
     const char *rsave;