Remove Export_static_lib_headers from codegen

It is not necessary to export headers from static libraries included
using whole_static_libs as that automatically exports the headers.

Test: m checkbuild
Bug: 134379140
Change-Id: Iea85dedf91f404739d12b3a7971cd87c02e1ab6d
Exempt-From-Owner-Approval: needed to fix build failure
2 files changed