apps: Move libevent dependency to src/apps/meson.build

libevent is a shared dependency between cam and lc-compliance, move it to
src/apps/. The shared dependency will be used to condition compilation
of source files in an upcoming application static library.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

src/apps/cam/meson.build

@@ -1,8 +1,6 @@
 # SPDX-License-Identifier: CC0-1.0
 
-libevent = dependency('libevent_pthreads', required : get_option('cam'))
-
-if not libevent.found()
+if opt_cam.disabled() or not libevent.found()
     cam_enabled = false
     subdir_done()
 endif

src/apps/lc-compliance/meson.build

@@ -1,10 +1,9 @@
 # SPDX-License-Identifier: CC0-1.0
 
-libevent = dependency('libevent_pthreads', required : get_option('lc-compliance'))
 libgtest = dependency('gtest', required : get_option('lc-compliance'),
                       fallback : ['gtest', 'gtest_dep'])
 
-if not (libevent.found() and libgtest.found())
+if opt_lc_compliance.disabled() or not libevent.found() or not libgtest.found()
     lc_compliance_enabled = false
     subdir_done()
 endif

src/apps/meson.build

@@ -1,5 +1,15 @@
 # SPDX-License-Identifier: CC0-1.0
 
+opt_cam = get_option('cam')
+opt_lc_compliance = get_option('lc-compliance')
+
+# libevent is needed by cam and lc-compliance. As they are both feature options,
+# they can't be combined with simple boolean logic.
+libevent = dependency('libevent_pthreads', required : opt_cam)
+if not libevent.found()
+    libevent = dependency('libevent_pthreads', required : opt_lc_compliance)
+endif
+
 subdir('lc-compliance')
 
 subdir('cam')