cmake: fix detection when openmp is enabled

Author: stkw0

kissfft-config.cmake.in

@@ -66,14 +66,19 @@ foreach(_kissfft_datatype simd int16 int32 float double)
 endforeach()
 
 if(_kissfft_datatype_detected)
-    if(NOT TARGET kissfft::kissfft-${_kissfft_datatype_detected})
-        message(FATAL_ERROR "kissfft with datatype=${_kissfft_datatype_detected} is not installed")
+    if(TARGET kissfft::kissfft-${_kissfft_datatype_detected}-openmp)
+	set(_kissfft_openmp_detected "-openmp")
     endif()
+
+    if(NOT TARGET kissfft::kissfft-${_kissfft_datatype_detected}${_kissfft_openmp_detected})
+        message(FATAL_ERROR "kissfft with datatype=${_kissfft_datatype_detected}${_kissfft_openmp_detected} is not installed")
+    endif()
+
     if(TARGET kissfft::kissfft)
         message(SEND_ERROR "kissfft::kissfft already exists. You cannot use 2 find_package's with datatype that are visible to eachother.")
     else()
         add_library(kissfft::kissfft INTERFACE IMPORTED)
-        set_property(TARGET kissfft::kissfft PROPERTY INTERFACE_LINK_LIBRARIES kissfft::kissfft-${_kissfft_datatype_detected})
+        set_property(TARGET kissfft::kissfft PROPERTY INTERFACE_LINK_LIBRARIES kissfft::kissfft-${_kissfft_datatype_detected}${_kissfft_openmp_detected})
     endif()
 endif()