qemu-common.h: Document cutils.c string functions Add documentation comments for various utility string functions which we have implemented in util/cutils.c: pstrcpy() strpadcpy() pstrcat() strstart() stristart() qemu_strnlen() qemu_strsep() Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>