Use -icf=0 for older BOLT compatibility

Author: ashm-dev

Misc/NEWS.d/next/Build/2026-04-21-17-27-52.gh-issue-148832.Kx9aQ1.rst

@@ -1,4 +1,4 @@
 Fix :option:`--enable-bolt` build by switching the default BOLT flag from
-``-icf=1`` to ``-icf=safe``. ``-icf=1`` folds address-taken functions and
+``-icf=1`` to ``-icf=0``. ``-icf=1`` folds address-taken functions and
 breaks type-slot dispatch, crashing on :mod:`list` and :mod:`tuple`
 concatenation. Patched by Shamil Abdulaev.

configure

@@ -2255,7 +2255,7 @@ then
      -reorder-blocks=ext-tsp
      -reorder-functions=cdsort
      -split-functions
-     -icf=safe
+     -icf=0
      -inline-all
      -split-eh
      -reorder-functions-use-hot-size