selftest/reproducible: Don't call sync between each file compare

Calling sync between each file compare is horrible performance wise
as we compare thousands of files. We don't care about IO latency here
so disable.

(From OE-Core rev: 25f78abd8bbeb201fd9452e7983e015027954948)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/lib/oeqa/selftest/cases/reproducible.py

@@ -123,7 +123,7 @@ def compare_file(reference, test, diffutils_sysroot):
         result.status = MISSING
         return result
 
-    r = runCmd(['cmp', '--quiet', reference, test], native_sysroot=diffutils_sysroot, ignore_status=True)
+    r = runCmd(['cmp', '--quiet', reference, test], native_sysroot=diffutils_sysroot, ignore_status=True, sync=False)
 
     if r.status:
         result.status = DIFFERENT