Upgraded the dwmblocks patch for statuscmd which changes the signalling

mechanism from SIGUSR1 to SIGRTMIN which is likely to cause issues for
those that already have a working setup. A compatibility option has been
added which changes this back to SIGUSR1. Note that configuration was
also changed.

This was ref. reported issue #114.

patch/bar_dwmblocks.c

@@ -1,31 +1,50 @@
-static int dwmblockssig;
-pid_t dwmblockspid = 0;
+static int statussig;
+pid_t statuspid = -1;
 
-int
-getdwmblockspid()
+pid_t
+getstatusbarpid()
 {
-	char buf[16];
-	FILE *fp = popen("pidof -s dwmblocks", "r");
-	if (fgets(buf, sizeof(buf), fp));
-	pid_t pid = strtoul(buf, NULL, 10);
+	char buf[32], *str = buf, *c;
+	FILE *fp;
+
+	if (statuspid > 0) {
+		snprintf(buf, sizeof(buf), "/proc/%u/cmdline", statuspid);
+		if ((fp = fopen(buf, "r"))) {
+			fgets(buf, sizeof(buf), fp);
+			while ((c = strchr(str, '/')))
+				str = c + 1;
+			fclose(fp);
+			if (!strcmp(str, STATUSBAR))
+				return statuspid;
+		}
+	}
+	if (!(fp = popen("pidof -s "STATUSBAR, "r")))
+		return -1;
+	fgets(buf, sizeof(buf), fp);
 	pclose(fp);
-	dwmblockspid = pid;
-	return pid != 0 ? 0 : -1;
+	return strtol(buf, NULL, 10);
 }
 
 void
-sigdwmblocks(const Arg *arg)
+sigstatusbar(const Arg *arg)
 {
 	union sigval sv;
-	sv.sival_int = (dwmblockssig << 8) | arg->i;
-	if (!dwmblockspid)
-		if (getdwmblockspid() == -1)
-			return;
 
-	if (sigqueue(dwmblockspid, SIGUSR1, sv) == -1) {
+	if (!statussig)
+		return;
+	if ((statuspid = getstatusbarpid()) <= 0)
+		return;
+
+	#if BAR_DWMBLOCKS_SIGUSR1_PATCH
+	sv.sival_int = (statussig << 8) | arg->i;
+	if (sigqueue(statuspid, SIGUSR1, sv) == -1) {
 		if (errno == ESRCH) {
-			if (!getdwmblockspid())
-				sigqueue(dwmblockspid, SIGUSR1, sv);
+			if (!getstatusbarpid())
+				sigqueue(statuspid, SIGUSR1, sv);
 		}
 	}
+	#else
+	sv.sival_int = arg->i;
+	sigqueue(statuspid, SIGRTMIN+statussig, sv);
+	#endif // BAR_DWMBLOCKS_SIGUSR1_PATCH
 }