soong_zip: set local header crc for symlinks

Getting a crc into the local header requires setting it before writing
the payload, or using a streaming data header after the payload with
the crc.  Stored (uncompressed) entries are not allowed to use a
streaming data header.

Symlinks are always stored uncompressed, so set the crc in the file
header before writing the payload.

Test: m checkbuild
Test: zipdetails on zip with symlink created with soong_zip has same
      crc in local header and central header.
Bug: 110716403
Change-Id: I66c5d41f0a5b23b828d6a03a3790afedc5a97625