Add ld-library-path meson option

meson.build

@@ -120,6 +120,8 @@ else
 endif
 add_project_arguments('-DSWAY_VERSION=@0@'.format(version), language: 'c')
 
+add_project_arguments('-D_LD_LIBRARY_PATH="@0@"'.format(get_option('ld-library-path')), language: 'c')
+
 sway_inc = include_directories('include')
 
 subdir('include')

meson_options.txt

@@ -1,4 +1,5 @@
 option('sway-version', type : 'string', description: 'The version string reported in `sway --version`.')
+option('ld-library-path', type: 'string', value: '', description: 'The LD_LIBRARY_PATH environment variable.')
 option('default-wallpaper', type: 'boolean', value: true, description: 'Install the default wallpaper.')
 option('zsh-completions', type: 'boolean', value: true, description: 'Install zsh shell completions.')
 option('bash-completions', type: 'boolean', value: true, description: 'Install bash shell completions.')