Fixes search within mount points, resulting in error "No such
directory".

Closes #190

libicu.a depends on libutil.a.

No longer a problem with NDK r16.

Android native code should be position-independent.

The NDK build scripts use "-fpic" instead of "-fPIC" for ARM, but that
doesn't work with FFmpeg's assembly code, because it requires
R_ARM_MOVW_ABS_NC which is unavailable with "-fpic".

By telling clang which implementation to use, we avoid the dependency
on libstdc++.so.

Work around automake warning:

    Makefile.am:310: warning: variable 'JAVA_SOURCES' is defined but no program or
    Makefile.am:310: library has 'JAVA' as canonical name (possible typo)

Closes #195

Fixes thread sanitizer warnings.

This attribute shall be used only for IsInside() to make this safe
against a race condition described in #188:

> There is no requirement on the implementation that the ID of the
> created thread be available before the newly created thread starts
> executing.

http://pubs.opengroup.org/onlinepubs/009695399/functions/pthread_create.html):

This means that on some pthread implementations (e.g. Haiku), the
assert(thread.IsInside()) could fail.

Closes #188

This method is only used inside assert().

Use the "==" operator instead of pthread_equal().

This allows us to eliminate two boolean flags which are there to avoid
race conditions, and made the thing so fragile that I got tons of
(correct) thread sanitizer warnings.

This completes the bug fix commit
2065e329; if we clear "queued" then we
must clear "queued_song" as well, or another variant of the assertion
fails.

MPD doesn't use this feature anyway.

This introduces a the new class MakeProject, which is used as a base
class for all Makefile based thirdparty libraries.