gnu: glibc: Update to 2.31.

gnu: glibc: Update to 2.31.

* gnu/packages/patches/glibc-supported-locales.patch: Adjust for upstream
changes.
* gnu/packages/patches/glibc-2.29-supported-locales.patch: New file, with
previous contents.
* gnu/packages/patches/gcc-4.9-libsanitizer-mode-size.patch,
gnu/packages/patches/gcc-6-libsanitizer-mode-size.patch,
gnu/packages/patches/gcc-7-libsanitizer-mode-size.patch,
gnu/packages/patches/gcc-8-libsanitizer-mode-size.patch,
gnu/packages/patches/gcc-9-libsanitizer-mode-size.patch: New files.
* gnu/local.mk (dist_patch_DATA): Adjust accordingly.
* gnu/packages/gcc.scm (gcc-4.9, gcc-5, gcc-6, gcc-7, gcc-8,
gcc-9)[source](patches): Add the respective patch files.
* gnu/packages/base.scm (glibc): Update to 2.31.
[source](patches): Remove obsolete.
(glibc-2.30): New public variable.
(glibc-2.29)[source](patches): Adjust for renamed patch file.