The library contains architecture specific versions of the clz functions
for arm and mips, but the fallback C version for other architectures is
pretty slow.

By using __builtin_clz on GCC (available since GCC 3.4), we get a
significant (20-40 %) speedup of the total running time on x86.

Speed difference: 5.1 s instead of 8.6 s for AAC-LC 128 kbit/s and
3.8 s instead of 4.9 s for HE-AACv2 32 kbit/s, on an i7.

When the addition overflowed, asserts were triggered later, where
the values were assumed to be non-negative.

Shifting by more than (or equal to) the variable length is
undefined in C.

These additions can overflow, triggering assertions later.

Mingw32 doesn't define the __int64 types.

Change-Id: Ia45add37be1bf85abde664fd6e382334a6bb4498

By default automake thinks the project is part of GNU and enforces the
presence of some files. By declaring the project foreign, we can
remove the 0-sized files.

Change-Id: Icc9c9ded1142232b5030183f2a653ee7cef632b5

Change-Id: If584e579464f28b97d50e51fc76ba654a5536c54

This simply means the comments are not copied into the executed
configure script.

Unless configure uses $host there is no reason to call it directly.

Change-Id: If139d0d1cf6f9fdfb0ebc477d2152b9f5f49f566

Mingw32 doesn't define the __int64 types.

While the source is C++, it doesn't use anything from the C++
runtime, so by building with -fno-exceptions -fno-rtti, the
dynamic library doesn't have to be linked to libstdc++. This
also simplifies things for users of the static library.

These correspond to different VBR modes.

This avoids name clashes with the similarly named files in
libSBRdec, when building all libraries with one single
automake file.

Change-Id: If97c7482bffaab4a21cd2fb8341f2939f19d3bbd

Change-Id: I9d9ab17121e2db58f8a4ba4b40e14cab629b1a7e

Change-Id: I42a702487e6db4953dca0027710ea4fe266052fd
Also:
 - Removed dead code in several source files.
 - Minor changes in comments.
 - No functional changes. No changes in executed code.
 - Added documentation PDFs.

Fixes:
- Don't throw error for invalid bitrate but limit to functional value
- More robust ASC parsing
- More robust handling of corrupt bitstreams
- Handle multiple raw access units

Change-Id: Ib49fe2545ff4185fe924126da702fe84ac5c2d87

License boilerplate update to follow.

Change-Id: I2810460c11a58b6d148d84673cc031f3685e79b5