Make emulator binaries unstripped by default.

Ensure that android-configure.sh/android-rebuild.sh generated
unstripped binaries by default. This means the binaries will
contain debug symbols, which will help getting accurate stack
traces during crashes or debugging.

This also adds a --strip option to the scripts to get back to
the old behaviour.

http://b.android.com/78663

Change-Id: If9c81bd983b26aba11054b7f2cfdff8267475fbf
Merge "Make emulator binaries unstripped by default."