PATCH: [gh #17185] Improper 'unescaped lbrace' msg

This warning is simply deleted.  The possible places where an unescaped
left brace is illegal has been scaled back to avoid breaking more
existing code, and this context will remain legal.

regcomp.c

@@ -11938,16 +11938,7 @@ S_reg(pTHX_ RExC_state_t *pRExC_state, I32 paren, I32 *flagp, U32 depth)
                 goto parse_rest;
             } /* end switch */
 	}
-	else {
-            if (*RExC_parse == '{') {
-                ckWARNregdep(RExC_parse + 1,
-                            "Unescaped left brace in regex is "
-                            "deprecated here (and will be fatal "
-                            "in Perl 5.32), passed through");
-            }
-            /* Not bothering to indent here, as the above 'else' is temporary
-             * */
-        if (!(RExC_flags & RXf_PMf_NOCAPTURE)) {   /* (...) */
+        else if (!(RExC_flags & RXf_PMf_NOCAPTURE)) {   /* (...) */
 	  capturing_parens:
 	    parno = RExC_npar;
 	    RExC_npar++;
@@ -12014,7 +12005,6 @@ S_reg(pTHX_ RExC_state_t *pRExC_state, I32 paren, I32 *flagp, U32 depth)
             /* with RXf_PMf_NOCAPTURE treat (...) as (?:...) */
             paren = ':';
 	    ret = 0;
-	}
         }
     }
     else                        /* ! paren */

t/re/reg_mesg.t

@@ -701,7 +701,6 @@ my @deprecated = (
  '/^{/'          => "",
  '/foo|{/'       => "",
  '/foo|^{/'      => "",
- '/foo({bar)/'   => 'Unescaped left brace in regex is deprecated here (and will be fatal in Perl 5.32), passed through {#} m/foo({{#}bar)/',
  '/foo(:?{bar)/' => "",
  '/\s*{/'        => "",
  '/a{3,4}{/'     => "",