cmd.exe: Only search for supplied command as-is if it includes an extension.

Files with no extensions cannot be run as-is. This enables a directory
with 'fred' and 'fred.bat' to correctly run fred.bat if just fred is
executed.

programs/cmd/wcmdmain.c

@@ -877,9 +877,12 @@ void WCMD_run_program (char *command, int called) {
     strcat(thisDir, stemofsearch);
     pos = &thisDir[strlen(thisDir)]; /* Pos = end of name */
 
+    /* 1. If extension supplied, see if that file exists */
+    if (extensionsupplied) {
       if (GetFileAttributes(thisDir) != INVALID_FILE_ATTRIBUTES) {
         found = TRUE;
       }
+    }
 
     /* 2. Any .* matches? */
     if (!found) {