Move EbmlWriter to video folder and enable only if libvpx is available.

openscad.pro

@@ -341,7 +341,6 @@ HEADERS += src/version_check.h \
            src/svg.h \
            src/video.h \
            src/video/video_png.h \
-	   src/EbmlWriter.h \
            \
            src/lodepng.h \
            src/OffscreenView.h \
@@ -420,7 +419,6 @@ SOURCES += \
            src/boost-utils.cc \
            src/video.cc \
            src/video/video_png.cc \
-	   src/EbmlWriter.cpp \
            src/PlatformUtils.cc \
            src/LibraryInfo.cc \
            \

vpx.pri

@@ -38,8 +38,8 @@ isEmpty(VPX_LIBPATH) {
   LIBS += $$VPX_LIBS
   DEFINES += ENABLE_VIDEO_VPX
 
-  HEADERS += src/video/video_vpx.h
-  SOURCES += src/video/video_vpx.cc
+  HEADERS += src/video/EbmlWriter.h src/video/video_vpx.h
+  SOURCES += src/video/EbmlWriter.cpp src/video/video_vpx.cc
 }
 
 }