Add support for libunarr detection and move include/detection logic to unarr-wrapper.pri

compressed_archive/unarr/unarr-wrapper.pri

@@ -6,8 +6,27 @@ HEADERS += $$PWD/extract_delegate.h \
 
 SOURCES += $$PWD/compressed_archive.cpp \
 
-#static build (no lib)
-include(unarr.pro)
+unix:!macx:exists (/usr/include/unarr.h) {
+		message(Using system provided unarr installation)
+		LIBS+=-lunarr
+		}
+else:macx:exists (../../dependencies/unarr/libunarr.dynlib) {
+		LIBS += -L../../dependencies/unarr/ -lunarr
+		}
 
-#for system libunarr.so
-#LIBS+=-lunarr
+else:win32:exists (../../dependencies/unarr/unarr.dll) {
+		LIBS += -L../../dependencies/unarr/ -lunarr
+		}
+
+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)
+		}
+	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)
+		}