Update precompiled pdfium for mac to chromium/3071 and add version info file with minimal build instructions

compressed_archive/unarr/unarr-wrapper.pri

@@ -0,0 +1,40 @@
+INCLUDEPATH += $$PWD
+DEPENDPATH += $$PWD
+
+HEADERS += $$PWD/extract_delegate.h \
+			$$PWD/compressed_archive.h \
+
+SOURCES += $$PWD/compressed_archive.cpp \
+
+unix:!macx:exists (/usr/include/unarr.h) {
+		message(Using system provided unarr installation)
+		LIBS+=-lunarr
+		DEFINES+=use_unarr
+		}
+else:macx:exists (../../dependencies/unarr/macx/libunarr.a) {
+		message(Found prebuilt unarr library in dependencies directory.)
+		INCLUDEPATH += $$PWD/../../dependencies/unarr/macx
+		LIBS += -L$$PWD/../../dependencies/unarr/macx -lunarr -lz -lbz2
+		DEFINES+=use_unarr
+		}
+
+else:win32:exists (../../dependencies/unarr/win/unarr.h) {
+		message(Found prebuilt unarr library in dependencies directory.)
+		INCLUDEPATH += $$PWD/../../dependencies/unarr/win
+		LIBS += -L../../dependencies/unarr/win/ -lunarr
+		DEFINES+=use_unarr
+		}
+
+else:exists ($$PWD/unarr-master) {
+		message(Found unarr source-code)
+		message(Unarr will be build as a part of YACReader)
+		
+		#qmake based unarr build system
+		#this should only be used for testing or as a last resort
+		include(unarr.pro)
+		DEFINES+=use_unarr
+		}
+	else {
+		error(Missing dependency: unarr decrompression backend. Please install libunarr on your system\
+		or provide a copy of the unarr source code in compressed_archive/unarr/unarr-master)
+		}