Assorted clean up in endgames

No functional change.
Union of 2 changes that failed with good score

This is a union of 2 changes:

A tweak of recaptures limit from Joona Kiiski
http://tests.stockfishchess.org/tests/view/52166d7c0ebc59319a242400

and a tweak of move count pruning from Leonid Pechenik
http://tests.stockfishchess.org/tests/view/5217c7e60ebc59319a242456

The set passed both short TC at 30+0.05
LLR: 2.96 (-2.94,2.94)
Total: 18936 W: 3723 L: 3566 D: 11647

And the usual long TC at 60+0.05
LLR: 2.95 (-2.94,2.94)
Total: 48962 W: 8837 L: 8487 D: 31638

bench: 3453945
Improve ARM compatibility

STANDALONE-TOOLCHAIN.html in Android NDK says:

It is recommended to use the -mthumb compiler flag to force the generation
of 16-bit Thumb-1 instructions (the default being 32-bit ARM ones).

If you want to target the 'armeabi-v7a' ABI, you will need ensure that the
following two flags are being used:

  CFLAGS='-march=armv7-a -mfloat-abi=softfp'

Note: The first flag enables Thumb-2 instructions, and the second one
      enables H/W FPU instructions while ensuring that floating-point
      parameters are passed in core registers, which is critical for
      ABI compatibility. Do *not* use these flags separately!

Thanks to Peter Osterlund for pointout this doc and for showing me
an example Makefile to follow.

No functional change.
Don't use lpthread for Android

Thanks to Peter Osterlund for the feedback.

No functional change.