fix EGL_CLIENT_STRING

it should read OpenGL_ES (with an underscore)

Bug: 6529643

Change-Id: I7caf07793bffe5a8dcceaff496a222077486fc87
diff --git a/opengl/libagl/egl.cpp b/opengl/libagl/egl.cpp
index 92d32a2..e6d065a 100644
--- a/opengl/libagl/egl.cpp
+++ b/opengl/libagl/egl.cpp
@@ -794,7 +794,7 @@
 #define VERSION_MINOR 2
 static char const * const gVendorString     = "Google Inc.";
 static char const * const gVersionString    = "1.2 Android Driver 1.2.0";
-static char const * const gClientApiString  = "OpenGL ES";
+static char const * const gClientApiString  = "OpenGL_ES";
 static char const * const gExtensionsString =
         "EGL_KHR_image_base "
         // "KHR_image_pixmap "