Remove ifneq MINGW condition around man page installation. We don't do

OS-dependent conditions in Makefiles anymore and I doubt this is correct.
If it turns out to be a problem it can easily be fixed.

Originally committed as revision 7028 to svn://svn.ffmpeg.org/ffmpeg/trunk

Makefile

@@ -132,12 +132,10 @@ wininstaller: all install
 
 # install man from source dir if available
 install-man:
-ifneq ($(CONFIG_MINGW),yes)
 	if [ -f doc/ffmpeg.1 ] ; then \
 	    install -d "$(mandir)/man1" ; \
 	    install -m 644 $(MANPAGES) "$(mandir)/man1" ; \
 	fi
-endif
 
 install-vhook:
 	$(MAKE) -C vhook install