builtin::trim: remove never executed code

builtin::trim is always XS, never an OP, so the TARGLEX optimization
doesn't apply.

builtin.c

@@ -275,27 +275,21 @@ XS(XS_builtin_trim)
 
     dest = TARG;
 
-    if (SvPOK(dest) && (dest == source)) {
-        sv_chop(dest, (const char *)start);
-        SvCUR_set(dest, len);
-    }
-    else {
-        SvUPGRADE(dest, SVt_PV);
-        SvGROW(dest, len + 1);
+    SvUPGRADE(dest, SVt_PV);
+    SvGROW(dest, len + 1);
 
-        Copy(start, SvPVX(dest), len, U8);
-        SvPVX(dest)[len] = '\0';
-        SvPOK_only_UTF8(dest);
-        SvCUR_set(dest, len);
+    Copy(start, SvPVX(dest), len, U8);
+    SvPVX(dest)[len] = '\0';
+    SvPOK_only_UTF8(dest);
+    SvCUR_set(dest, len);
 
-        if (DO_UTF8(source))
-            SvUTF8_on(dest);
-        else
-            SvUTF8_off(dest);
+    if (DO_UTF8(source))
+        SvUTF8_on(dest);
+    else
+        SvUTF8_off(dest);
 
-        if (SvTAINTED(source))
-            SvTAINT(dest);
-    }
+    if (SvTAINTED(source))
+        SvTAINT(dest);
 
     SvSETMAGIC(dest);