llvm-libunwind does not have cmake nor pkg-config files, not great
but switch to cc.find for simplicity with meson feature-type options
--- a/src/meson.build
+++ b/src/meson.build
@@ -1,3 +1,3 @@
 ### Common dependencies
-unwind = dependency('libunwind', required: get_option('unwind'))
+unwind = cc.find_library('libunwind', required: get_option('unwind'))
 libexecinfo = cc.find_library('execinfo', required: false)