Fix target opts to remove prefix on the win32 dll

CMake didn't like the previous attempt

CMakeLists.txt

@@ -33,15 +33,6 @@ SET(LIB_BUILD_VERSION "38")
 SET(LIB_VERSION "${LIB_MAJOR_VERSION}.${LIB_MINOR_VERSION}.${LIB_BUILD_VERSION}")
 
 
-IF("${WIN32}")
-    SET(LIBNAME openal32)
-    SET(TARGET_OPTS "PREFIX \"\"")
-ELSE()
-    SET(LIBNAME openal)
-    SET(TARGET_OPTS "")
-ENDIF()
-
-
 CHECK_TYPE_SIZE("long" SIZEOF_LONG)
 CHECK_TYPE_SIZE("long long" SIZEOF_LONG_LONG)
 CHECK_TYPE_SIZE("unsigned int" SIZEOF_UINT)
@@ -267,10 +258,18 @@ CONFIGURE_FILE(
 ADD_DEFINITIONS(-DAL_BUILD_LIBRARY)
 
 # Build a shared library
+IF("${WIN32}")
+    SET(LIBNAME openal32)
+ELSE()
+    SET(LIBNAME openal)
+ENDIF()
+
 ADD_LIBRARY(${LIBNAME} SHARED ${OPENAL_OBJS} ${ALC_OBJS})
 SET_TARGET_PROPERTIES(${LIBNAME} PROPERTIES VERSION ${LIB_VERSION}
-                                            SOVERSION ${LIB_MAJOR_VERSION}
-                                            ${TARGET_OPTS})
+                                            SOVERSION ${LIB_MAJOR_VERSION})
+IF("${WIN32}")
+    SET_TARGET_PROPERTIES(${LIBNAME} PROPERTIES PREFIX "")
+ENDIF()
 
 TARGET_LINK_LIBRARIES(${LIBNAME} ${EXTRA_LIBS})