Latch LC_NUMERIC during critical sections

It is possible for operations on threaded perls which don't 'use locale'
to still change the locale.  This happens when calling
POSIX::localeconv() and I18N::Langinfo(), and in earlier perls, it can
happen for other operations when perl has been initialized with the
environment causing the various locale categories to not have a uniform
locale.

This commit causes the areas where the locale for this category should
predictably be in one or the other state to be a critical section where
another thread can't interrupt and change it.  This is a separate
mutex, so that only these particular operations will be held up.

1 files changed, 1 insertions, 0 deletions

diff --git a/sv.c b/sv.c
index 4377e95411..2c3da0fb7f 100644
--- a/sv.c
+++ b/sv.c
@@ -15235,6 +15235,7 @@ perl_clone_using(PerlInterpreter *proto_perl, UV flags,
     PL_in_utf8_CTYPE_locale = proto_perl->Iin_utf8_CTYPE_locale;
     PL_in_utf8_COLLATE_locale = proto_perl->Iin_utf8_COLLATE_locale;
     my_strlcpy(PL_locale_utf8ness, proto_perl->Ilocale_utf8ness, sizeof(PL_locale_utf8ness));
+    PL_lc_numeric_mutex_depth = 0;
     /* Unicode features (see perlrun/-C) */
     PL_unicode		= proto_perl->Iunicode;