X11: Fix sonames for dynamically loaded libraries

Fixes #941.

README.md

@@ -150,6 +150,7 @@ information on what to include when reporting a bug.
                   a loader but no ICD (#916)
 - [X11] Replaced `_GLFW_HAS_XF86VM` compile-time option with dynamic loading
 - [X11] Bugfix: `glfwGetVideoMode` would segfault on Cygwin/X
+- [X11] Bugfix: Dynamic X11 library loading did not use full sonames (#941)
 - [Linux] Bugfix: Event processing did not detect joystick disconnection (#932)
 - [Cocoa] Added support for Vulkan window surface creation via
           [MoltenVK](https://moltengl.com/moltenvk/) (#870)

src/x11_init.c

@@ -459,7 +459,7 @@ static void detectEWMH(void)
 //
 static GLFWbool initExtensions(void)
 {
-    _glfw.x11.vidmode.handle = dlopen("libXxf86vm.so", RTLD_LAZY | RTLD_GLOBAL);
+    _glfw.x11.vidmode.handle = dlopen("libXxf86vm.so.1", RTLD_LAZY | RTLD_GLOBAL);
     if (_glfw.x11.vidmode.handle)
     {
         _glfw.x11.vidmode.QueryExtension = (PFN_XF86VidModeQueryExtension)
@@ -558,7 +558,7 @@ static GLFWbool initExtensions(void)
         }
     }
 
-    _glfw.x11.x11xcb.handle = dlopen("libX11-xcb.so", RTLD_LAZY | RTLD_GLOBAL);
+    _glfw.x11.x11xcb.handle = dlopen("libX11-xcb.so.1", RTLD_LAZY | RTLD_GLOBAL);
     if (_glfw.x11.x11xcb.handle)
     {
         _glfw.x11.x11xcb.XGetXCBConnection = (PFN_XGetXCBConnection)