generate pkg-config file only on Unixes (Linux, BSD, Apple)

src/CMakeLists.txt

@@ -367,11 +367,13 @@ if(MSVC)
 endif()
 ENDIF(WITH_WPCAP)
 
-configure_file(
+if(UNIX)
+    configure_file(
         ${CMAKE_CURRENT_LIST_DIR}/libiec61850.pc.in
         ${CMAKE_CURRENT_BINARY_DIR}/libiec61850.pc @ONLY
-)
+    )
-install(FILES libiec61850.pc DESTINATION "${CMAKE_INSTALL_PREFIX}/share/pkgconfig")
+    install(FILES libiec61850.pc DESTINATION "${CMAKE_INSTALL_PREFIX}/share/pkgconfig")
+endif()
 
 install (TARGETS iec61850 iec61850-shared
 	RUNTIME DESTINATION bin COMPONENT Applications