Export headers from libdexfile_external

libdexfile_external didn't export any header. This caused the abi dumper
to (conservatively) treat all header files in its include paths as
exported headers. As a result, the dump became unnecessary large due to
the transitively exported headers.

Fixing this by explicitly specifying the exported headers.

Bug: 140166209
Test: m
Change-Id: Icd6db4705bee6c38646f5d0251aeb65b19d00327
1 file changed