Android NDK update, bgfx side (#2960)

* Android: Add local copy of native_app_glue, patched to compile as C++.

* Android: List android-x86_64 configuration in makefile

* Android: Build shared-lib and examples by default

* Docs: Update Android build prerequisites

* CI: Add Android builds

* CI: **DO NOT MERGE** pick bx/PR with android support update

scripts/example-common.lua

@@ -81,6 +81,11 @@ project ("example-common")
 		}
 	end
 
+	configuration { "android-*" }
+		includedirs {
+			path.join(BGFX_DIR, "3rdparty/native_app_glue")
+		}
+
 	configuration { "osx* or ios* or tvos*" }
 		files {
 			path.join(BGFX_DIR, "examples/common/**.mm"),