Save space by inlining misc.c functions.
* kern/misc.c (grub_iswordseparator): Made static.
* kern/misc.c (grub_strcat): Moved from here ...
* include/grub/misc.h (grub_strcat): ... here. Inlined.
* kern/misc.c (grub_strncat): Moved from here ...
* include/grub/misc.h (grub_strncat): ... here. Inlined.
* kern/misc.c (grub_strcasecmp): Moved from here ...
* include/grub/misc.h (grub_strcasecmp): ... here. Inlined.
* kern/misc.c (grub_strncasecmp): Moved from here ...
* include/grub/misc.h (grub_strncasecmp): ... here. Inlined.
* kern/misc.c (grub_isalpha): Moved from here ...
* include/grub/misc.h (grub_isalpha): ... here. Inlined.
* kern/misc.c (grub_isdigit): Moved from here ...
* include/grub/misc.h (grub_isdigit): ... here. Inlined.
* kern/misc.c (grub_isgraph): Moved from here ...
* include/grub/misc.h (grub_isgraph): ... here. Inlined.
* kern/misc.c (grub_tolower): Moved from here ...
* include/grub/misc.h (grub_tolower): ... here. Inlined.