[patch] usr.bin/mg/region.c: Set default shell path if SHELL is NULL

[lux]

Index: region.c
===================================================================
RCS file: /cvs/src/usr.bin/mg/region.c,v
retrieving revision 1.40
diff -u -p -r1.40 region.c
--- region.c    8 Mar 2023 04:43:11 -0000       1.40
+++ region.c    27 Mar 2023 16:48:08 -0000
@@ -21,6 +21,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
+#include <paths.h>
 
 #include "def.h"
 
@@ -486,9 +487,8 @@ shellcmdoutput(char* const argv[], char*
                return (FALSE);
        }
 
-       shellp = getenv("SHELL");
-
-       ret = pipeio(shellp, argv, text, len, bp);
+       ret = pipeio((shellp = getenv("SHELL")) == NULL ? _PATH_BSHELL
: shellp,
+                    argv, text, len, bp);
 
        if (ret == TRUE) {
                eerase();