Merge branch 'hotfix.libdir.fftw' into 'master'

use CMAKE_INSTALL_LIBDIR for FFTW

See merge request flexi/flexi!766

Author: marblin

posti/CMakeLists.txt

@@ -71,8 +71,8 @@ IF(POSTI_RP_VISUALIZE OR POSTI_CHANNEL_FFT OR POSTI_HIT_INIT OR POSTI_HIT_FILTER
         BUILD_IN_SOURCE 1
       )
     SET(FFTW_INCLUDE_DIR ${POSTI_FFTWDIR}/build/include)
-    SET(FFTW_LIBRARY     ${POSTI_FFTWDIR}/build/lib/libfftw3.a)
-    SET(FFTW_OMP_LIBRARY ${POSTI_FFTWDIR}/build/lib/libfftw3_omp.a)
+    SET(FFTW_LIBRARY     ${POSTI_FFTWDIR}/build/${CMAKE_INSTALL_LIBDIR}/libfftw3.a)
+    SET(FFTW_OMP_LIBRARY ${POSTI_FFTWDIR}/build/${CMAKE_INSTALL_LIBDIR}/libfftw3_omp.a)
     SET_PROPERTY(DIRECTORY PROPERTY CLEAN_NO_CUSTOM 1)
     LIST(APPEND SELFBUILTEXTERNALS fftw)
   ELSE()