* m4/realloc.m4 (gl_FUNC_REALLOC_0_NONNULL):
Add comment about _LINUX_SOURCE_COMPAT.
# gl_FUNC_REALLOC_0_NONNULL
# -------------------------
# Replace realloc if realloc (..., 0) returns null.
+# Modules that use this macro directly or indirectly should depend
+# on extensions-aix, so that _LINUX_SOURCE_COMPAT gets defined
+# before this macro gets invoked. This helps if !(__VEC__ || __AIXVEC),
+# and doesn't hurt otherwise.
AC_DEFUN([gl_FUNC_REALLOC_0_NONNULL],
[
AC_REQUIRE([gl_STDLIB_H_DEFAULTS])