extract bionic kernel headers

This patch correctly extracts bionic kernel headers instead
of those under external/kernel-headers/original/.

From external/kernel-headers/original/README.txt:
  This directory contains the original kernel headers that are used to generate Bionic's "cleaned-up" user-land headers.
  They are mostly covered by the GPLv2 + exception, and thus cannot be distributed as part of the platform itself.
  (NOTE: The cleaned up headers do not contain copyrightable information and are distributed with Bionic)
add vimline with style

Signed-off-by: Adrian Negreanu <adrian.m.negreanu@intel.com>
more detailed usage message

Signed-off-by: Adrian Negreanu <adrian.m.negreanu@intel.com>
rpm complains when headers have executable bit set

Signed-off-by: Adrian Negreanu <adrian.m.negreanu@intel.com>
add makefile for android headers

Signed-off-by: Adrian Negreanu <adrian.m.negreanu@intel.com>
no need for check_header_exists

Signed-off-by: Adrian Negreanu <adrian.m.negreanu@intel.com>
dynamically add hooks from glibc

The hook table contains
a. functions that need parameter conversion
   (like parameters of type FILE*, or pthread_mutex_t*)
b. some of the pthread_ functions we know to work from glibc.
   The pthread functions that we don't have in the hook table,
   when called by client code, will cause a crash.

If a symbol is not found in the hook table, it's searched
in libc.so.6. If it's not found there, then we fallback to bionic.

So far, this patch covers bionic{libc,libdl} and a part of libthread_db.
Still to be covered is libm, libstdc++ and linker.

For debugging purposes, one can use HYBRIS_FROM_BIONIC to
force a symbol to be used from Bionic.

So far, I only need longjmp and setjmp from bionic{libc}, everything else
being called from (e)glibc.

Tested on nexus 4 as:
  HYBRIS_EGLPLATFORM=hwcomposer \
  ./ARMHF/bin/test_hwcomposer

Signed-off-by: Adrian Negreanu <adrian.m.negreanu@intel.com>
hwcomposer-egl.pc: link with hybris-hardware

Signed-off-by: Adrian Negreanu <adrian.m.negreanu@intel.com>