* In an effort to modernize build configurations to the new Soong
  system, we need to upgrade existing Android.mk files to Android.bp
* This file is done by using the following steps:
  1. Manually removing all *_sources from Android.mk, because
     of the unusual make logic they use
  2. Running the auto-conversion tool:
     androidmk Android.mk > Android.bp
  3. Editing the result Android.bp:
     3.1. Writing the "srcs" list
     3.2. Removing the escaping around -Wno-#warnings in cflags,
          because those are not needed anymore
     3.3. Renamed local_include_dirs to export_include_dirs to
          facilititate the inclusion of header files.
          It appears users of libFraunhoferAAC are using header
          files from all include directories, hence the renaming.

Test: Code compilation ("mm" in external/aac, and "make" in top-directory)
Bug: b/32958753 b/34454142
Change-Id: Ie89f73722908e8734f4b88f1407952311ec064af