[sysprof] build: make libunwind optional

[Christian Hergert <chergert src gnome org>]

commit e06638d665e1b4ac85feea88c53113cb877c460d
Author: Christian Hergert <chergert redhat com>
Date:   Mon Feb 17 12:02:44 2020 -0800

    build: make libunwind optional

 meson.build                        | 8 +++++---
 meson_options.txt                  | 3 +++
 src/libsysprof/preload/meson.build | 5 ++++-
 3 files changed, 12 insertions(+), 4 deletions(-)
---
diff --git a/meson.build b/meson.build
index 13ef5a4..231445d 100644
--- a/meson.build
+++ b/meson.build
@@ -89,9 +89,11 @@ if cc.has_header('execinfo.h')
   config_h.set10('HAVE_EXECINFO_H', true)
 endif
 
-libunwind_dep = dependency('libunwind-generic', required: false)
-if libunwind_dep.found()
-  config_h.set10('ENABLE_LIBUNWIND', libunwind_dep.found())
+if get_option('libunwind')
+  libunwind_dep = dependency('libunwind-generic', required: false)
+  if libunwind_dep.found()
+    config_h.set10('ENABLE_LIBUNWIND', libunwind_dep.found())
+  endif
 endif
 
 # Development build setup
diff --git a/meson_options.txt b/meson_options.txt
index f30c783..623945c 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -29,3 +29,6 @@ option('debugdir', type: 'string',
 
 # If Yelp documentation should be installed
 option('help', type: 'boolean')
+
+# Disable use of libunwind
+option('libunwind', type: 'boolean')
diff --git a/src/libsysprof/preload/meson.build b/src/libsysprof/preload/meson.build
index 596fc79..91b09a0 100644
--- a/src/libsysprof/preload/meson.build
+++ b/src/libsysprof/preload/meson.build
@@ -1,9 +1,12 @@
 libsysprof_memory_preload_deps = [
   cc.find_library('dl', required: false),
   libsysprof_capture_dep,
-  libunwind_dep,
 ]
 
+if get_option('libunwind')
+  libsysprof_memory_preload_deps += [libunwind_dep]
+endif
+
 libsysprof_memory_preload_sources = [
   'sysprof-memory-collector.c',
 ]