Changed CMake scripts to work correctly if the FFTW threading support was...

Changed CMake scripts to work correctly if the FFTW threading support was built into the main library instead of a separate library

cmake_modules/FindFFTW.cmake

@@ -20,6 +20,5 @@ find_library (FFTW_THREADS_LIBRARY NAMES fftw3f_threads)
 # all listed variables are TRUE
 include (FindPackageHandleStandardArgs)
 find_package_handle_standard_args (FFTW DEFAULT_MSG FFTW_LIBRARY FFTW_INCLUDES)
-find_package_handle_standard_args (FFTW_THREADS DEFAULT_MSG FFTW_THREADS_LIBRARY FFTW_INCLUDES)
 
 mark_as_advanced (FFTW_LIBRARY FFTW_THREADS_LIBRARY FFTW_INCLUDES)

plugins/cpupme/CMakeLists.txt

@@ -85,7 +85,10 @@ IF (UNIX AND CMAKE_BUILD_TYPE MATCHES Debug)
 ELSE (UNIX AND CMAKE_BUILD_TYPE MATCHES Debug)
     SET(MAIN_OPENMM_LIB ${OPENMM_LIBRARY_NAME})
 ENDIF (UNIX AND CMAKE_BUILD_TYPE MATCHES Debug)
-TARGET_LINK_LIBRARIES(${SHARED_TARGET} ${MAIN_OPENMM_LIB} ${PTHREADS_LIB} ${FFTW_LIBRARY} ${FFTW_THREADS_LIBRARY})
+TARGET_LINK_LIBRARIES(${SHARED_TARGET} ${MAIN_OPENMM_LIB} ${PTHREADS_LIB} ${FFTW_LIBRARY})
+IF (${FFTW_THREADS_LIBRARY})
+    TARGET_LINK_LIBRARIES(${SHARED_TARGET} ${FFTW_THREADS_LIBRARY})
+ENDIF (${FFTW_THREADS_LIBRARY})
 SET_TARGET_PROPERTIES(${SHARED_TARGET} PROPERTIES COMPILE_FLAGS "-DOPENMM_PME_BUILDING_SHARED_LIBRARY")
 
 INSTALL_TARGETS(/lib/plugins RUNTIME_DIRECTORY /lib/plugins ${SHARED_TARGET})