Let x option synopsis be printed in grdfilter independently of having OMP or not.

Author: joa-quim

src/gmt_dev.h

@@ -154,6 +154,7 @@ struct GMT_CTRL; /* forward declaration of GMT_CTRL */
 #include "gmt_nan.h"            /* Machine-dependent macros for making and testing NaNs */
 #include "gmt_error.h"          /* Only contains error codes */
 #include "gmt_synopsis.h"       /* Only contains macros for synopsis lines */
+#include "gmt_glib.h"           /* Make the GMT_xg_OPT define visible, even if HAVE_GLIB_GTHREAD is not defined */
 #include "gmt_version.h"        /* Only contains the current GMT version number */
 #include "gmt_project.h"        /* Define GMT->current.proj and GMT->current.map.frame structures */
 #include "gmt_grd.h"            /* Define grd file header structure */

src/gmt_glib.h

@@ -30,6 +30,7 @@
    These are used only GLIB based multi-threading */
 
 #ifndef GMT_GLIB_H
+#define GMT_GLIB_H
 
 #ifdef HAVE_GLIB_GTHREAD
 #include <glib.h>

src/gmt_init.c

@@ -8124,9 +8124,9 @@ void gmtlib_explain_options (struct GMT_CTRL *GMT, char *options) {
 
 #if defined(GMT_MP_ENABLED)
 		case 'y':	/* Number of threads (reassigned from -x in GMT_Option) */
-			if (strlen (GMT_x_OPT) > 1) {	/* Only print this if it is in fact available */
+			if (strlen(GMT_x_OPT) > 1 || strlen(GMT_xg_OPT) > 1) {	/* Only print this if it is in fact available */
 				cores = gmtlib_get_num_processors();
-				GMT_Usage (API, 1, "\n%s", GMT_x_OPT);
+				(strlen(GMT_x_OPT) > 1) ? GMT_Usage(API, 1, "\n%s", GMT_x_OPT) : GMT_Usage(API, 1, "\n%s", GMT_xg_OPT);
 				GMT_Usage (API, -2, "Limit the number of cores used in multi-threaded algorithms [Default uses all %d cores]. "
 					"If <n> is negative then we select (%d - <n>) cores (or at least 1).", cores, cores);
 			}

src/grdfilter.c

@@ -47,7 +47,7 @@ Use option -x to set the number of threads. e.g. -x2, -x4, ... or -xa to use all
 
 #include "gmt_dev.h"
 #include "longopt/grdfilter_inc.h"
-#include "gmt_glib.h"
+//#include "gmt_glib.h"		/* Now included in gmt_dev.h */
 
 #define THIS_MODULE_CLASSIC_NAME	"grdfilter"
 #define THIS_MODULE_MODERN_NAME	"grdfilter"