Fix test_gl error reporting (#764)

* Fix test_gl error reporting

Overwriting 'error' variable after check for Msaa/Depth support was clearing
the error counter incremented after failure in test_image_format_write. In
effect the test might return 0 even if there were errors.

* Fix variable name

* Fix formatting

* Fix formatting
diff --git a/test_conformance/gl/test_images_write_common.cpp b/test_conformance/gl/test_images_write_common.cpp
index cd48df4..9bbb257 100644
--- a/test_conformance/gl/test_images_write_common.cpp
+++ b/test_conformance/gl/test_images_write_common.cpp
@@ -763,16 +763,16 @@
             get_base_gl_target(targets[ tidx ]) == GL_TEXTURE_2D_MULTISAMPLE_ARRAY)
         {
             bool supports_msaa;
-            error = supportsMsaa(context, &supports_msaa);
-            if( error != 0 ) return error;
+            int errorInGetInfo = supportsMsaa(context, &supports_msaa);
+            if (errorInGetInfo != 0) return errorInGetInfo;
             if (!supports_msaa) return 0;
         }
         if (formats[ fidx ].formattype == GL_DEPTH_COMPONENT ||
             formats[ fidx ].formattype == GL_DEPTH_STENCIL)
         {
             bool supports_depth;
-            error = supportsDepth(context, &supports_depth);
-            if( error != 0 ) return error;
+            int errorInGetInfo = supportsDepth(context, &supports_depth);
+            if (errorInGetInfo != 0) return errorInGetInfo;
             if (!supports_depth) return 0;
         }
 #endif