graphics: add IMapper to complement IAllocator

IMapper is loaded in-process and is defined in C++ instead of HIDL.  To
guarantee binary compability, the interface is a struct of function
pointers instead of a class of pure virtual member functions.  The
functions pointed to by the function pointers must also have C-linkage and
have all of their parameters PODs.

Implementations are expected to be installed to

  /oem/lib/hw/android.hardware.graphics.mapper.hallib.so
  /vendor/lib/hw/android.hardware.graphics.mapper.hallib.so
  /system/lib/hw/android.hardware.graphics.mapper.hallib.so
  (lib64 instead of lib for 64-bit implementations)

The loader will look for the symbol "HALLIB_FETCH_Interface" and use it to
fetch the interface.

Test: make android.hardware.graphics.mapper@2.0
Change-Id: I3a2c7a6ce18a90adda6df2d89559c957a122fdf0
diff --git a/graphics/mapper/2.0/Android.bp b/graphics/mapper/2.0/Android.bp
new file mode 100644
index 0000000..3718503
--- /dev/null
+++ b/graphics/mapper/2.0/Android.bp
@@ -0,0 +1,15 @@
+genrule {
+    name: "android.hardware.graphics.mapper@2.0_genc++_headers",
+    cmd: "cp $in $genDir/android/hardware/graphics/mapper/2.0",
+    srcs: ["IMapper.h", "types.h"],
+    out: [
+        "android/hardware/graphics/mapper/2.0/IMapper.h",
+        "android/hardware/graphics/mapper/2.0/types.h",
+    ],
+}
+
+cc_library_static {
+    name: "android.hardware.graphics.mapper@2.0",
+    generated_headers: ["android.hardware.graphics.mapper@2.0_genc++_headers"],
+    export_generated_headers: ["android.hardware.graphics.mapper@2.0_genc++_headers"],
+}