Log when malloc functions fail.

This shouldn't happen often, and resulting failures can be hard to debug.

From the bionic unit tests now:

  W libc    : malloc(18446744073709551615) failed: returning null pointer
  W libc    : calloc(18446744073709551615, 100) failed: returning null pointer
  W libc    : calloc(1, 18446744073709551615) failed: returning null pointer
  W libc    : calloc(18446744073709551615, 18446744073709551615) failed: returning null pointer
  W libc    : calloc(2, 18446744073709551615) failed: returning null pointer
  W libc    : calloc(18446744073709551615, 2) failed: returning null pointer
  W libc    : memalign(4096, 18446744073709551615) failed: returning null pointer
  W libc    : realloc(0x0, 18446744073709551615) failed: returning null pointer
  W libc    : realloc(0x75d7526070, 18446744073709551615) failed: returning null pointer
  W libc    : reallocaray(0x0, 9223372036854775812, 2) failed: returning null pointer
  W libc    : reallocaray(0x0, 2, 9223372036854775812) failed: returning null pointer

Bug: http://b/12821450
Test: ran tests
Change-Id: Ib176814404f4ba1297416dd3e1edd721bf59aeed