Add a variable to override the default library type with

CMakeLists.txt

@@ -333,8 +333,11 @@ CONFIGURE_FILE(
 
 ADD_DEFINITIONS(-DAL_BUILD_LIBRARY)
 
-# Build a shared library
-ADD_LIBRARY(${LIBNAME} SHARED ${OPENAL_OBJS} ${ALC_OBJS})
+# Build a library
+IF(NOT LIBTYPE)
+    SET(LIBTYPE SHARED)
+ENDIF()
+ADD_LIBRARY(${LIBNAME} ${LIBTYPE} ${OPENAL_OBJS} ${ALC_OBJS})
 SET_TARGET_PROPERTIES(${LIBNAME} PROPERTIES VERSION ${LIB_VERSION}
                                             SOVERSION ${LIB_MAJOR_VERSION})
 IF(WIN32)