Merge upstream version 25.1

Merge upstream version 25.1

Remove patches that are no longer needed:
  0006-Look-for-NEWS-in-order-to-find-etc-rather-than-GNU.patch
  0008-Emacs-won-t-assume-grep-supports-GREP_OPTIONS.patch
  0009-Emacs-should-no-longer-hang-during-large-yanks.patch
  0010-ELF-unexec-Correct-section-header-index.patch
  0011-ELF-unexec-Tidy-code.patch
  0012-ELF-unexec-Merge-Alpha-and-MIPS-COFF-debug-handling.patch
  0013-ELF-unexec-Symbol-table-patching.patch
  0014-ELF-unexec-_OBJC_-symbols-in-bss-sections.patch
  0015-ELF-unexec-R_-_NONE-relocs.patch
  0016-ELF-unexec-Drive-from-PT_LOAD-header-rather-than-sec.patch
  0017-ELF-unexec-Don-t-insert-a-new-section.patch
  0018-src-unexelf.c-NEW_PROGRAM_H-Remove-unused-macro-Bug-.patch
  0019-ELF-unexec-align-section-header.patch
  0020-Emacs-should-show-GTK-icons-again.patch
  0021-Emacs-should-work-with-gcc-5.2-and-newer.patch
  0022-Emacs-should-work-with-glibc-2.24-on-ppc64.patch