[Driver] Generate .eh_frame_hdr for static executables too.

Summary: libgcc won't unwind without an .eh_frame_hdr section.

Reviewers: srhines, chandlerc

Reviewed By: chandlerc

Subscribers: chandlerc, cfe-commits

Differential Revision: https://reviews.llvm.org/D43203

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@325733 91177308-0d34-0410-b5e6-96231b3b80d8
(cherry picked from commit 30f9051d)