[m-rev.] diff: Don't require --no-allow-ho-insts-as-modes yet.

[Peter Wang]

Allow some time to update to a version of the compiler that supports
the new option.

library/LIB_FLAGS.in:
    As above.

diff --git a/library/LIB_FLAGS.in b/library/LIB_FLAGS.in
index 8130617c6..d51c37c52 100644
--- a/library/LIB_FLAGS.in
+++ b/library/LIB_FLAGS.in
@@ -17,7 +17,6 @@
 --no-warn-stdlib-shadowing
 --warn-dead-predicates
 --no-warn-inferred-erroneous
---no-allow-ho-insts-as-modes
 --no-mercury-stdlib-dir
 --no-detect-libgrades
 --strict-sequential 
-- 
2.39.0