Avoid repeated lines of the form

Program scripts/rust/rust_root_crate.sh found: YES (/home/pbonzini/work/upstream/qemu/scripts/rust/rust_root_crate.sh)

in the meson logs.

Reviewed-by: Junjie Mao <junjie.mao@hotmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 meson.build | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/meson.build b/meson.build
index ffd78b6cbb3..f85bc22fbdd 100644
--- a/meson.build
+++ b/meson.build
@@ -3977,6 +3977,7 @@ endif
 
 
 feature_to_c = find_program('scripts/feature_to_c.py')
+rust_root_crate = find_program('scripts/rust/rust_root_crate.sh')
 
 if host_os == 'darwin'
   entitlement = find_program('scripts/entitlement.sh')
@@ -4078,7 +4079,7 @@ foreach target : target_dirs
     if crates.length() > 0
       rlib_rs = custom_target('rust_' + target.underscorify() + '.rs',
                               output: 'rust_' + target.underscorify() + '.rs',
-                              command: [find_program('scripts/rust/rust_root_crate.sh')] + crates,
+                              command: [rust_root_crate, crates],
                               capture: true,
                               build_by_default: true,
                               build_always_stale: true)
-- 
2.46.2