Better initial sample rate setup, remove hard-coded default rate and use device info matching /w fallback

cmake/Modules/FindJack.cmake

@@ -0,0 +1,50 @@
+# Try to find JACK
+# This will define the following variables:
+#
+#  JACK_FOUND - Whether Jack was found.
+#  JACK_INCLUDE_DIRS - Jack include directories.
+#  JACK_LIBRARIES - Jack libraries.
+
+include(FindPackageHandleStandardArgs)
+
+if(JACK_LIBRARIES AND JACK_INCLUDE_DIRS)
+
+  # in cache already
+  set(JACK_FOUND TRUE)
+
+else()
+
+  find_package(PkgConfig)
+  if(PKG_CONFIG_FOUND)
+    pkg_check_modules(_JACK jack)
+  endif(PKG_CONFIG_FOUND)
+
+  find_path(JACK_INCLUDE_DIR
+    NAMES
+      jack/jack.h
+    PATHS
+      ${_JACK_INCLUDEDIR}
+  )
+  
+  find_library(JACK_LIBRARY
+    NAMES
+      jack
+    PATHS
+      ${_JACK_LIBDIR}
+  )
+
+  set(JACK_INCLUDE_DIRS
+    ${JACK_INCLUDE_DIR}
+  )
+
+  set(JACK_LIBRARIES
+    ${JACK_LIBRARY}
+  )
+
+  find_package_handle_standard_args(Jack DEFAULT_MSG JACK_LIBRARIES JACK_INCLUDE_DIRS)
+
+  # show the JACK_INCLUDE_DIRS and JACK_LIBRARIES variables only in the advanced view
+  mark_as_advanced(JACK_INCLUDE_DIR JACK_LIBRARY JACK_INCLUDE_DIRS JACK_LIBRARIES)
+
+endif()
+