Updated FFMPEG to 3.3.3; Fixed unistd.h issue in ffmpeg build

ports/ffmpeg/CONTROL

@@ -1,5 +1,5 @@
 Source: ffmpeg
-Version: 3.2.4-4
+Version: 3.3.3
 Build-Depends: openssl
 Description: a library to decode, encode, transcode, mux, demux, stream, filter and play pretty much anything that humans and machines have created.
   FFmpeg is the leading multimedia framework, able to decode, encode, transcode, mux, demux, stream, filter and play pretty much anything that humans and machines have created. It supports the most obscure ancient formats up to the cutting edge. No matter if they were designed by some standards committee, the community or a corporation. It is also highly portable: FFmpeg compiles, runs, and passes our testing infrastructure FATE across Linux, Mac OS X, Microsoft Windows, the BSDs, Solaris, etc. under a wide variety of build environments, machine architectures, and configurations.

ports/ffmpeg/portfile.cmake

@@ -4,11 +4,11 @@ if(VCPKG_LIBRARY_LINKAGE STREQUAL "static")
 endif()
 
 include(vcpkg_common_functions)
-set(SOURCE_PATH ${CURRENT_BUILDTREES_DIR}/src/ffmpeg-3.2.4)
+set(SOURCE_PATH ${CURRENT_BUILDTREES_DIR}/src/ffmpeg-3.3.3)
 vcpkg_download_distfile(ARCHIVE
-    URLS "http://ffmpeg.org/releases/ffmpeg-3.2.4.tar.bz2"
-    FILENAME "ffmpeg-3.2.4.tar.bz2"
-    SHA512 ba5004d0f2659faa139c7dbf2f0fc6bab1d4e017d919f4ac271a5d2e8e4a3478909176e3a4d1ad33ddf2f62ab28dd9e00ce9be1399efb7cb3276dde79134cdaa
+    URLS "http://ffmpeg.org/releases/ffmpeg-3.3.3.tar.bz2"
+    FILENAME "ffmpeg-3.3.3.tar.bz2"
+    SHA512 1cc63bf73356f4e618c0d3572a216bdf5689f10deff56b4262f6d740b0bee5a4b3eac234f45fca3d4d2da77903a507b4fba725b76d2d2070f31b6dae9e7a2dab
 )
 vcpkg_extract_source_archive(${ARCHIVE})
 vcpkg_apply_patches(
@@ -62,6 +62,8 @@ endif()
 set(OPTIONS_DEBUG "") # Note: --disable-optimizations can't be used due to http://ffmpeg.org/pipermail/libav-user/2013-March/003945.html
 set(OPTIONS_RELEASE "")
 
+set(OPTIONS "${OPTIONS} --extra-cflags=-DHAVE_UNISTD_H=0")
+
 if(VCPKG_LIBRARY_LINKAGE STREQUAL "dynamic")
     set(OPTIONS "${OPTIONS} --disable-static --enable-shared")
     if (VCPKG_CMAKE_SYSTEM_NAME STREQUAL "WindowsStore")