fsstorage: missing #include

-----
  CC       addons/fsstorage.lo
addons/fsstorage.c: In function 'WriteCatalog':
addons/fsstorage.c:543:5: error: implicit declaration of function 'getpid' [-Werror=implicit-function-declaration]
cc1: some warnings being treated as errors
make.exe[5]: *** [addons/fsstorage.lo] Error 1
-----

Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>
os2: fix one instance mode

Files are not added, and a first instance is blocked.

Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>
configure: add -Zhigh-mem linker flag for OS/2

When converting 1920x1080p mp4 using x264, x264 complains that it failed
to allocate memory. This flags makes it happy.

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