[MU4 Issue] Build fail with `-DBUILD_JACK=ON`

[hfiguiere]

Describe the bug Build fail with -DBUILD_JACK=ON because the macro PKGCONFIG1 is unknown

To Reproduce Steps to reproduce the behavior:

1. configre the build on Linux wtih -DBUILD_JACK=ON
2. build
3. Build fail because PKGCONFIG1 isn't known.

Expected behavior Either it find jack or it doesn't.

Screenshots n/a

Platform information

• OS: Linux

Additional context

You need this patch:

diff --git a/build/cmake/FindJack.cmake b/build/cmake/FindJack.cmake
index 6713e3aeef..58cc8cee14 100644
--- a/build/cmake/FindJack.cmake
+++ b/build/cmake/FindJack.cmake
@@ -3,6 +3,7 @@
 ## Find JACK >= JACK_MIN_VERSION
 ##
 
+include(UsePkgConfig1)
 
 IF(BUILD_JACK)
      IF(MINGW OR MSVC)