Remove redundant extern declarations, fixes the warnings:
vo_vesa.c:55: warning: redundant redeclaration of #monitor_hfreq_str#
video_out.h:252: warning: previous declaration of #monitor_hfreq_str# was here
vo_vesa.c:56: warning: redundant redeclaration of #monitor_vfreq_str#
video_out.h:253: warning: previous declaration of #monitor_vfreq_str# was here
vo_vesa.c:57: warning: redundant redeclaration of #monitor_dotclock_str#
video_out.h:254: warning: previous declaration of #monitor_dotclock_str# was here
git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@25551 b3059339-0415-0410-9bf9-f77b7e298cf2