16-byte boundary, as required by the x86-64 ABI, before calling
grub_main. In some cases, GCC emits code that assumes this
alignment, which crashes if not aligned. The EFI firmware is also
entitled to assume that stack alignment without checking.
handling to copy the killed characters to the kill buffer as
UCS4 stored as grub_uint32_t rather than as 8-bit characters
stored as char. Eliminates UCS4 truncation and corruption
observed when killing characters with Ctrl-u and yanking them
back with Ctrl-y.