Perl_quadmath_format_single(): fix off-by-1 err

RT #134369

This function checks that a floating format string (%f, %e etc) on
-Dusequadmath builds has the 'Q' qualifier , and if not adds it.

However, the "adding" code  allocates a new buffer that is one byte too
short, which this commit fixes.

In practice it doesn't matter, as in core, this function is only ever
called when the 'Q' is already present.

1 files changed, 1 insertions, 1 deletions

diff --git a/util.c b/util.c
index 165d13a39e..359f3b6d85 100644
--- a/util.c
+++ b/util.c
@@ -4931,7 +4931,7 @@ Perl_quadmath_format_single(const char* format)
         return NULL;
     if (format[len - 2] != 'Q') {
         char* fixed;
-        Newx(fixed, len + 1, char);
+        Newx(fixed, len + 2, char);
         memcpy(fixed, format, len - 1);
         fixed[len - 1] = 'Q';
         fixed[len    ] = format[len - 1];