patch 8.1.1267: cannot check if GPM mouse support is working

Problem:    Cannot check if GPM mouse support is working.
Solution:   Add the "mouse_gpm_enable" feature.

Author: brammool

runtime/doc/eval.txt

@@ -10532,6 +10532,7 @@ modify_fname		Compiled with file name modifiers. |filename-modifiers|
 mouse			Compiled with support mouse.
 mouse_dec		Compiled with support for Dec terminal mouse.
 mouse_gpm		Compiled with support for gpm (Linux console mouse)
+mouse_gpm_enabled	GPM mouse is working
 mouse_netterm		Compiled with support for netterm mouse.
 mouse_pterm		Compiled with support for qnx pterm mouse.
 mouse_sysmouse		Compiled with support for sysmouse (*BSD console mouse)

src/evalfunc.c

@@ -6810,6 +6810,10 @@ f_has(typval_T *argvars, typval_T *rettv)
 	else if (STRICMP(name, "netbeans_enabled") == 0)
 	    n = netbeans_active();
 #endif
+#ifdef FEAT_MOUSE_GPM
+	else if (STRICMP(name, "mouse_gpm_enabled") == 0)
+	    n = gpm_enabled();
+#endif
 #if defined(FEAT_TERMINAL) && defined(MSWIN)
 	else if (STRICMP(name, "terminal") == 0)
 	    n = terminal_enabled();

src/os_unix.c

@@ -7022,7 +7022,7 @@ mch_rename(const char *src, const char *dest)
 }
 #endif /* !HAVE_RENAME */
 
-#ifdef FEAT_MOUSE_GPM
+#if defined(FEAT_MOUSE_GPM) || defined(PROTO)
 /*
  * Initializes connection with gpm (if it isn't already opened)
  * Return 1 if succeeded (or connection already opened), 0 if failed
@@ -7058,13 +7058,22 @@ gpm_open(void)
     return 1; /* already open */
 }
 
+/*
+ * Returns TRUE if the GPM mouse is enabled.
+ */
+    int
+gpm_enabled(void)
+{
+    return gpm_flag && gpm_fd >= 0;
+}
+
 /*
  * Closes connection to gpm
  */
     static void
 gpm_close(void)
 {
-    if (gpm_flag && gpm_fd >= 0) /* if Open */
+    if (gpm_enabled())
 	Gpm_Close();
 }
 

src/proto/os_unix.pro

@@ -72,6 +72,7 @@ int mch_expand_wildcards(int num_pat, char_u **pat, int *num_file, char_u ***fil
 int mch_has_exp_wildcard(char_u *p);
 int mch_has_wildcard(char_u *p);
 int mch_rename(const char *src, const char *dest);
+int gpm_enabled(void);
 int mch_libcall(char_u *libname, char_u *funcname, char_u *argstring, int argint, char_u **string_result, int *number_result);
 void setup_term_clip(void);
 void start_xterm_trace(int button);

src/version.c

@@ -767,6 +767,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1267,
 /**/
     1266,
 /**/