Fixed CMake finding VOLK functions

cmake/modules/FindVolk.cmake

@@ -26,8 +26,11 @@ FIND_LIBRARY(
 
 # Some functions are not defined in old volk versions
 
+INCLUDE(FindPackageHandleStandardArgs)
+FIND_PACKAGE_HANDLE_STANDARD_ARGS(VOLK DEFAULT_MSG VOLK_LIBRARIES VOLK_INCLUDE_DIRS)
+MARK_AS_ADVANCED(VOLK_LIBRARIES VOLK_INCLUDE_DIRS VOLK_DEFINITIONS)
 
-IF(NOT ${VOLK_LIBRARIES} STREQUAL "")
+IF(VOLK_FOUND)
   SET(CMAKE_REQUIRED_LIBRARIES ${VOLK_LIBRARIES} m)
   CHECK_FUNCTION_EXISTS_MATH(volk_32f_index_max_16u HAVE_VOLK_MAX_FUNCTION)
   CHECK_FUNCTION_EXISTS_MATH(volk_32f_x2_max_32f HAVE_VOLK_MAX_VEC_FUNCTION)
@@ -130,7 +133,4 @@ IF(NOT ${VOLK_LIBRARIES} STREQUAL "")
   IF(${HAVE_VOLK_ATAN_FUNCTION})
     SET(VOLK_DEFINITIONS "${VOLK_DEFINITIONS}; HAVE_VOLK_ATAN_FUNCTION")
   ENDIF()
-  INCLUDE(FindPackageHandleStandardArgs)
-  FIND_PACKAGE_HANDLE_STANDARD_ARGS(VOLK DEFAULT_MSG VOLK_LIBRARIES VOLK_INCLUDE_DIRS)
-  MARK_AS_ADVANCED(VOLK_LIBRARIES VOLK_INCLUDE_DIRS VOLK_DEFINITIONS)
-ENDIF(NOT ${VOLK_LIBRARIES} STREQUAL "")
+ENDIF(VOLK_FOUND)