Advertise EGL_ANDROID_GLES_layers extension

Presence of the extension means libEGL will scan for layers and
enumerate their entrypoints by calling AndroidGLESLayer_Initialize
and AndroidGLESLayer_GetProcAddress.

Since tools must determine layering support before fully loading
libEGL, the following call will return extension strings without
loading vendor drivers:

    eglQueryString(EGL_NO_DISPLAY, EGL_EXTENSIONS);

Bug: 110883880
Test: atest CtsGpuToolsHostTestCases
Test: Connect with GLES layers using GAPID and RenderDoc
Change-Id: Ib79193b3a0ac3dffacd51bc677b81c07ffcced93
diff --git a/opengl/libs/EGL/egl_platform_entries.cpp b/opengl/libs/EGL/egl_platform_entries.cpp
index 872631f..34262f3 100644
--- a/opengl/libs/EGL/egl_platform_entries.cpp
+++ b/opengl/libs/EGL/egl_platform_entries.cpp
@@ -139,7 +139,8 @@
 char const * const gClientExtensionString =
         "EGL_EXT_client_extensions "
         "EGL_KHR_platform_android "
-        "EGL_ANGLE_platform_angle";
+        "EGL_ANGLE_platform_angle "
+        "EGL_ANDROID_GLES_layers";
 // clang-format on
 
 // extensions not exposed to applications but used by the ANDROID system