Fixed SDRplay source of OSX

sdrplay_source/CMakeLists.txt

@@ -26,6 +26,11 @@ if (MSVC)
 else (MSVC)
     find_package(PkgConfig)
 
+    # Include it because for some reason pkgconfig doesn't look here?
+    if (${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
+        target_include_directories(sdrplay_source PUBLIC "/usr/local/include")
+    endif()
+
     target_link_libraries(sdrplay_source PRIVATE sdrplay_api)
 endif ()