Updates to cmake files:

- new FindEmbedded - it looks for presence of RPI or IMX6
- if Embedded found:
    - OpenGL find is skipped (this might find libGL.so on IMX6 otherwise)
    - pkgconfig is skipped (this might find Mesa libs on RPI if installed)

(that means, for IMX6 GLES2 will be used, on RPI as well with preference
of /opt/vc if found)

CMakeLists.txt

@@ -13,7 +13,11 @@ find_package(platform REQUIRED)
 add_definitions(-DUSE_DEMUX)
 
 if(NOT WIN32)
-  find_package(OpenGL)
+  find_package(EMBEDDED)
+  if(NOT EMBEDDED_FOUND)
+    find_package(OpenGL)
+  endif()
+
   if(OPENGL_FOUND)
     set(INCLUDES ${OPENGL_INCLUDE_DIR})
     set(DEPLIBS ${OPENGL_LIBRARIES})

FindEMBEDDED.cmake

@@ -0,0 +1,12 @@
+# - Try to find embedded platforms (RPI/IMX6)
+# Once done this will define
+#
+#  EMBEDDED_FOUND        - system is RPI / IMX6 and we most probably want to compile for GLES2 support
+#                          (don't configure for OpenGL)
+
+string(REGEX MATCH "^arm" TARGET_ARCH_ARM "${CMAKE_SYSTEM_PROCESSOR}")
+if(NOT CMAKE_CROSSCOMPILING AND NOT TARGET_ARCH_ARM)
+  return()
+endif(NOT CMAKE_CROSSCOMPILING AND NOT TARGET_ARCH_ARM)
+
+find_path(EMBEDDED_FOUND NAMES include/linux/imxfb.h include/bcm_host.h PATHS /opt/vc)

FindOpenGLES2.cmake

@@ -6,9 +6,11 @@
 #  OPENGLES2_LIBRARIES    - Link these to use OpenGLES2
 
 find_package(PkgConfig)
-if(PKG_CONFIG_FOUND)
+if(PKG_CONFIG_FOUND AND NOT EMBEDDED_FOUND)
   pkg_check_modules(OpenGLES2 glesv2)
-endif(PKG_CONFIG_FOUND)
+elseif(EMBEDDED_FOUND)
+  set(CMAKE_PREFIX_PATH ${EMBEDDED_FOUND} ${CMAKE_PREFIX_PATH})
+endif(PKG_CONFIG_FOUND AND NOT EMBEDDED_FOUND)
 
 if(NOT OPENGLES2_FOUND)
   if("${CORE_SYSTEM_NAME}" STREQUAL "ios")