Mir: Fix broken build

Regression caused by e9560ef021.

src/CMakeLists.txt

@@ -48,10 +48,11 @@ elseif (_GLFW_WAYLAND)
         BASENAME pointer-constraints-unstable-v1)
 elseif (_GLFW_MIR)
     set(glfw_HEADERS ${common_HEADERS} mir_platform.h linux_joystick.h
-                     posix_time.h posix_tls.h xkb_unicode.h egl_context.h)
+                     posix_time.h posix_tls.h xkb_unicode.h egl_context.h
+                     osmesa_context.h)
     set(glfw_SOURCES ${common_SOURCES} mir_init.c mir_monitor.c mir_window.c
                      linux_joystick.c posix_time.c posix_tls.c xkb_unicode.c
-                     egl_context.c)
+                     egl_context.c osmesa_context.c)
 elseif (_GLFW_OSMESA)
     set(glfw_HEADERS ${common_HEADERS} null_platform.h null_joystick.h
                      posix_time.h posix_tls.h osmesa_context.h)

src/mir_platform.h

@@ -52,6 +52,7 @@ typedef VkBool32 (APIENTRY *PFN_vkGetPhysicalDeviceMirPresentationSupportKHR)(Vk
 #include "linux_joystick.h"
 #include "xkb_unicode.h"
 #include "egl_context.h"
+#include "osmesa_context.h"
 
 #define _glfw_dlopen(name) dlopen(name, RTLD_LAZY | RTLD_LOCAL)
 #define _glfw_dlclose(handle) dlclose(handle)

src/mir_window.c

@@ -405,10 +405,21 @@ int _glfwPlatformCreateWindow(_GLFWwindow* window,
 
     if (ctxconfig->client != GLFW_NO_API)
     {
-        if (!_glfwInitEGL())
-            return GLFW_FALSE;
-        if (!_glfwCreateContextEGL(window, ctxconfig, fbconfig))
-            return GLFW_FALSE;
+        if (ctxconfig->source == GLFW_EGL_CONTEXT_API ||
+            ctxconfig->source == GLFW_NATIVE_CONTEXT_API)
+        {
+            if (!_glfwInitEGL())
+                return GLFW_FALSE;
+            if (!_glfwCreateContextEGL(window, ctxconfig, fbconfig))
+                return GLFW_FALSE;
+        }
+        else if (ctxconfig->source == GLFW_OSMESA_CONTEXT_API)
+        {
+            if (!_glfwInitOSMesa())
+                return GLFW_FALSE;
+            if (!_glfwCreateContextOSMesa(window, ctxconfig, fbconfig))
+                return GLFW_FALSE;
+        }
     }
 
     return GLFW_TRUE;