base64: gcc-15 compile issue

When compiling grub-2.12 with gcc-15-20241208 the following line causes the following error: https://git.savannah.gnu.org/cgit/gnulib.git/tree/lib/base64.c#n62 ../../grub-core/lib/gnulib/base64.c:65:3: error: initializer-string for array of 'char' is too long [-Werror=unterminated-string-init

cross compiling with current gnulib fails on strcasecmp

Hi Team, Compiling nano 8.4 and diffutils 3.12 which are using a recent gnulib fail to build on Ubuntu 24.04. links: - https://lists.gnu.org/archive/html/bug-diffutils/2025-04/msg3.html - https://savannah.gnu.org/bugs/index.php?66978 This is tge error from diffutils: checking for strcasecmp