Remove GLVersion from GLAD header and make it static

Bug: chromium:877147
Change-Id: I9635fdf977dd13658a957bd247e453f3b6511dca
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/5520
Reviewed-by: Kai Ninomiya <kainino@chromium.org>
Commit-Queue: Austin Eng <enga@chromium.org>
diff --git a/third_party/glad/include/glad/glad.h b/third_party/glad/include/glad/glad.h
index 2825675..db5272d 100644
--- a/third_party/glad/include/glad/glad.h
+++ b/third_party/glad/include/glad/glad.h
@@ -81,8 +81,6 @@
 # endif
 #endif
 
-extern struct gladGLversionStruct GLVersion;
-
 GLAPI int gladLoadGL(void);
 
 GLAPI int gladLoadGLLoader(GLADloadproc);
diff --git a/third_party/glad/src/glad.c b/third_party/glad/src/glad.c
index 60e128f..90b440f 100644
--- a/third_party/glad/src/glad.c
+++ b/third_party/glad/src/glad.c
@@ -7,7 +7,7 @@
     APIs: gl=4.5
     Profile: core
     Extensions:
-        
+
     Loader: True
     Local files: False
     Omit khrplatform: False
@@ -152,7 +152,7 @@
     return status;
 }
 
-struct gladGLversionStruct GLVersion = { 0, 0 };
+static struct gladGLversionStruct GLVersion = { 0, 0 };
 
 #if defined(GL_ES_VERSION_3_0) || defined(GL_VERSION_3_0)
 #define _GLAD_IS_SOME_NEW_VERSION 1