Use alternate mirrors for glib and libslirp dependencies (#1078)

* glib: Use github mirror of glib repository

* Use qemu gitlab mirror of libslirp repository

.gitmodules

@@ -42,10 +42,10 @@
 	url = https://github.com/wolfSSL/wolfssl.git
 [submodule "FreeRTOS-Plus/ThirdParty/libslirp"]
 	path = FreeRTOS-Plus/ThirdParty/libslirp
-	url = https://gitlab.freedesktop.org/slirp/libslirp.git
+	url = https://gitlab.com/qemu-project/libslirp.git
 [submodule "FreeRTOS-Plus/ThirdParty/glib"]
 	path = FreeRTOS-Plus/ThirdParty/glib
-	url = https://gitlab.gnome.org/GNOME/glib.git
+	url = https://github.com/GNOME/glib.git
 [submodule "FreeRTOS-Plus/Source/Application-Protocols/coreMQTT-Agent"]
 	path = FreeRTOS-Plus/Source/Application-Protocols/coreMQTT-Agent
 	url = https://github.com/FreeRTOS/coreMQTT-Agent.git