Fix: unbreak compilation on OpenBSD - pt1

Mesa in OpenBSD don't show glGetQueryObjectui64v. We use
glXGetProcAddress for obtain the function pointer

src/backend/gl/gl_common.c

@@ -22,6 +22,8 @@
 #include "backend/backend_common.h"
 #include "backend/gl/gl_common.h"
 
+static PFNGLGETQUERYOBJECTUI64VPROC ptrglGetQueryObjectui64v = NULL;
+
 void gl_prepare(backend_t *base, const region_t *reg attr_unused) {
 	auto gd = (struct gl_data *)base;
 	glBeginQuery(GL_TIME_ELAPSED, gd->frame_timing[gd->current_frame_timing]);
@@ -1213,13 +1215,29 @@ bool gl_last_render_time(backend_t *base, struct timespec *ts) {
 		return false;
 	}
 
-	GLuint64 time;
-	glGetQueryObjectui64v(gd->frame_timing[gd->current_frame_timing ^ 1],
-	                      GL_QUERY_RESULT, &time);
-	ts->tv_sec = (long)(time / 1000000000);
-	ts->tv_nsec = (long)(time % 1000000000);
-	gl_check_err();
-	return true;
+	// We need obtain proc pointer for glGetQueryObjectui64v function.
+	// In OpenBSD this function no appear publicly, glXGetProcAddress resolve the issue.
+	if(ptrglGetQueryObjectui64v == NULL) {
+		ptrglGetQueryObjectui64v = (PFNGLGETQUERYOBJECTUI64VPROC)
+			glXGetProcAddress("glGetQueryObjectui64v");
+
+		GLuint64 time;
+		ptrglGetQueryObjectui64v(gd->frame_timing[gd->current_frame_timing ^ 1],
+					 GL_QUERY_RESULT, &time);
+		ts->tv_sec = (long)(time / 1000000000);
+		ts->tv_nsec = (long)(time % 1000000000);
+		gl_check_err();
+	}
+	else {
+		GLuint64 time;
+		ptrglGetQueryObjectui64v(gd->frame_timing[gd->current_frame_timing ^ 1],
+					 GL_QUERY_RESULT, &time);
+		ts->tv_sec = (long)(time / 1000000000);
+		ts->tv_nsec = (long)(time % 1000000000);
+		gl_check_err();
+	}
+
+ 	return true;
 }
 
 bool gl_image_op(backend_t *base, enum image_operations op, void *image_data,