meson: fix type of "relocatable" option

Since the option is of boolean type, the default value should be a boolean
rather than a string.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/meson_options.txt b/meson_options.txt
index c9baeda..0a99a05 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -101,7 +101,7 @@
        description: 'Verbose errors in case of CFI violation')
 option('multiprocess', type: 'feature', value: 'auto',
        description: 'Out of process device emulation support')
-option('relocatable', type : 'boolean', value : 'true',
+option('relocatable', type : 'boolean', value : true,
        description: 'toggle relocatable install')
 option('vfio_user_server', type: 'feature', value: 'disabled',
        description: 'vfio-user server support')