Revert "adb: append the libwinpthread COPYING to adb's NOTICE."

This reverts commit d3bf1a8d.

Reason for revert: Now Soong can handle NOTICE files for static libraries.

Bug: 36073965
Test: mma + visual check
Change-Id: I52ebd3518f4d15800f878a6401df2c3a2d6713eb