[ELF] Align the end of PT_GNU_RELRO to max-page-size instead of common-page-size

We picked common-page-size to match GNU ld. Recently, the resolution to GNU ld
https://sourceware.org/bugzilla/show_bug.cgi?id=28824 (milestone: 2.39) switched
to max-page-size so that the last page can be protected by RELRO in case the
system page size is larger than common-page-size.

Thanks to our two RW PT_LOAD scheme (D58892), switching to max-page-size does
not change file size (while GNU ld's scheme may increase file size).

Reviewed By: peter.smith

Differential Revision: https://reviews.llvm.org/D125410