mg: fix spacing in a few dobeep_msgs() calls

[Omar Polo]

as per subject, when dobeep_msgs() was introduced some places weren't
converted correctly: it already adds a space between the two
arguments, so no need to duplicate.

Index: extend.c
===================================================================
RCS file: /cvs/src/usr.bin/mg/extend.c,v
retrieving revision 1.79
diff -u -p -r1.79 extend.c
--- extend.c    30 Mar 2023 22:56:47 -0000      1.79
+++ extend.c    17 Apr 2023 10:00:55 -0000
@@ -493,7 +493,7 @@ redefine_key(int f, int n)
                return (FALSE);
        (void)strlcat(buf, tmp, sizeof(buf));
        if ((mp = name_map(tmp)) == NULL)
-               return (dobeep_msgs("Unknown map ", tmp));
+               return (dobeep_msgs("Unknown map", tmp));
 
        if (strlcat(buf, "key: ", sizeof(buf)) >= sizeof(buf))
                return (FALSE);
@@ -720,7 +720,7 @@ excline(char *line, int llen, int lnum)
                n = (int)nl;
        }
        if ((fp = name_function(funcp)) == NULL)
-               return (dobeep_msgs("Unknown function: ", funcp));
+               return (dobeep_msgs("Unknown function:", funcp));
 
        if (fp == bindtokey || fp == unbindtokey) {
                bind = BINDARG;
@@ -847,7 +847,7 @@ excline(char *line, int llen, int lnum)
                case BINDNEXT:
                        lp->l_text[lp->l_used] = '\0';
                        if ((curmap = name_map(lp->l_text)) == NULL) {
-                               (void)dobeep_msgs("No such mode: ", lp->l_text);
+                               (void)dobeep_msgs("No such mode:", lp->l_text);
                                status = FALSE;
                                free(lp);
                                goto cleanup;
Index: interpreter.c
===================================================================
RCS file: /cvs/src/usr.bin/mg/interpreter.c,v
retrieving revision 1.34
diff -u -p -r1.34 interpreter.c
--- interpreter.c       28 Jan 2022 06:18:41 -0000      1.34
+++ interpreter.c       17 Apr 2023 10:00:55 -0000
@@ -406,7 +406,7 @@ parsexp(char *begp, const char *par1, co
         * If no extant mg command found, just return.
         */
        if ((funcp = name_function(cmdp)) == NULL)
-               return (dobeep_msgs("Unknown command: ", cmdp));
+               return (dobeep_msgs("Unknown command:", cmdp));
 
        numparams = numparams_function(funcp);
        if (numparams == 0)