Only include strings.h in MinGW builds

* main.c:
* job.c: Include strings.h only if HAVE_STRINGS_H is defined.

* config.h.W32.template (HAVE_STRINGS_H): Define only for MinGW,
as MSVC doesn't have this header.

config.h.W32.template

@@ -268,7 +268,9 @@ this program.  If not, see <http://www.gnu.org/licenses/>.  */
 #define HAVE_STRICMP 1
 
 /* Define to 1 if you have the <strings.h> header file. */
+#ifdef __MINGW32__
 #define HAVE_STRINGS_H 1
+#endif
 
 /* Define to 1 if you have the <string.h> header file. */
 #define HAVE_STRING_H 1

job.c

@@ -29,7 +29,9 @@ this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
 /* Default shell to use.  */
 #ifdef WINDOWS32
+#ifdef HAVE_STRINGS_H
 #include <strings.h>	/* for strcasecmp, strncasecmp */
+#endif
 #include <windows.h>
 
 const char *default_shell = "sh.exe";

main.c

@@ -33,7 +33,9 @@ this program.  If not, see <http://www.gnu.org/licenses/>.  */
 #ifdef WINDOWS32
 # include <windows.h>
 # include <io.h>
+#ifdef HAVE_STRINGS_H
 # include <strings.h>	/* for strcasecmp */
+#endif
 # include "pathstuff.h"
 # include "sub_proc.h"
 # include "w32err.h"