emulator: enable opengl emulation modules

This patch defines BUILD_EMULATOR_OPENGL to 'true' to
enable the OpenGLES emulation modules under
development/tools/emulator/opengl to be built.

Change-Id: I130b5026909ce43578ead8bebe889075d90c4486
diff --git a/target/board/generic/BoardConfig.mk b/target/board/generic/BoardConfig.mk
index 64b1dbe..70f8585 100644
--- a/target/board/generic/BoardConfig.mk
+++ b/target/board/generic/BoardConfig.mk
@@ -33,3 +33,6 @@
 ifeq ($(HOST_OS),linux)
 WITH_DEXPREOPT := true
 endif
+
+# Build OpenGLES emulation guest and host libraries
+BUILD_EMULATOR_OPENGL := true
diff --git a/target/board/generic_x86/BoardConfig.mk b/target/board/generic_x86/BoardConfig.mk
index 0206434..9826973 100644
--- a/target/board/generic_x86/BoardConfig.mk
+++ b/target/board/generic_x86/BoardConfig.mk
@@ -26,3 +26,5 @@
 ifeq ($(HOST_OS),linux)
 WITH_DEXPREOPT := true
 endif
+# Build OpenGLES emulation host and guest libraries
+BUILD_EMULATOR_OPENGL := true