Setup XP_WIN, XP_UNIX, XP_MACOSX macros.
Setup XP_WIN, XP_UNIX, XP_MACOSX macros.

These macros were previously defined in mozilla-config.h, but we're
not supposed to include those files according to the mozilla devs.
However, the macros must be defined for npapi.h to define the
necessary platform-specific structures.  This patch sets up the
macros before including npapi.h.

Signed-off-by: Jean-Baptiste Kempf <7b85a41a628204b76aba4326273a3ccc74bd009a@videolan.org>

shyamalschandra/vlc,shyamalschandra/vlc,krichter722/vlc,krichter722/vlc,vlc-mirror/vlc,vlc-mirror/vlc,xkfz007/vlc,shyamalschandra/vlc,xkfz007/vlc,jomanmuk/vlc-2.2,vlc-mirror/vlc-2.1,krichter722/vlc,shyamalschandra/vlc,jomanmuk/vlc-2.1,xkfz007/vlc,shyamalschandra/vlc,vlc-mirror/vlc-2.1,vlc-mirror/vlc,vlc-mirror/vlc,jomanmuk/vlc-2.2,krichter722/vlc,jomanmuk/vlc-2.1,vlc-mirror/vlc-2.1,jomanmuk/vlc-2.1,vlc-mirror/vlc-2.1,shyamalschandra/vlc,jomanmuk/vlc-2.2,jomanmuk/vlc-2.1,xkfz007/vlc,vlc-mirror/vlc,jomanmuk/vlc-2.2,krichter722/vlc,jomanmuk/vlc-2.1,vlc-mirror/vlc-2.1,vlc-mirror/vlc,jomanmuk/vlc-2.1,jomanmuk/vlc-2.2,krichter722/vlc,shyamalschandra/vlc,krichter722/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,jomanmuk/vlc-2.2,vlc-mirror/vlc,jomanmuk/vlc-2.1,vlc-mirror/vlc-2.1,vlc-mirror/vlc-2.1,jomanmuk/vlc-2.2