Removed tens of annoying warnings about implicit declaration of memcpy(), strlen() and about unused variables. 


mysys/mf_casecnv.c:
  Removed annoying warnings about implicit declaration of memcpy(), strlen() and about unused variables
mysys/mf_qsort.c:
  Removed annoying warnings about implicit declaration of memcpy(), strlen() and about unused variables
readline/complete.c:
  Removed annoying warnings about implicit declaration of memcpy(), strlen() and about unused variables
readline/readline.c:
  Removed annoying warnings about implicit declaration of memcpy(), strlen() and about unused variables
readline/vi_mode.c:
  Removed annoying warnings about implicit declaration of memcpy(), strlen() and about unused variables