[committed] Adding missing prototype for __clzhi2 to xstormy port

[Jeff Law]

xstormy16 has failed since the c99 transition due to a missing prototype 
for __clzhi2 in the implementation of storm16_count_loaading_zeros.

This fixes the missing prototype.  Pushed to the trunk.
jeffcommit 9f7afa99c67f039e43019ebd08d14a7f01e2d89c
Author: Jeff Law <j...@ventanamicro.com>
Date:   Tue Jan 9 10:21:28 2024 -0700

    [committed] Adding missing prototype for __clzhi2 to xstormy port
    
    xstormy16 has failed since the c99 transition due to a missing prototype for
    __clzhi2 in the implementation of stormy16_count_leading_zeros.
    
    This fixes the missing prototype.  Pushed to the trunk.
    
    include/
            * longlong.h (__stormy16_count_leading_zeros): Add prototype for
            __clzhi2.

diff --git a/include/longlong.h b/include/longlong.h
index e4fe1d24144..b5dec95b7ed 100644
--- a/include/longlong.h
+++ b/include/longlong.h
@@ -1573,6 +1573,7 @@ extern UHItype __stormy16_count_leading_zeros (UHItype);
       for ((count) = 0, size = W_TYPE_SIZE; size; size -= 16)          \
        {                                                               \
          UHItype c;                                                    \
+         extern UHItype __clzhi2 (UHItype);                            \
                                                                        \
          c = __clzhi2 ((x) >> (size - 16));                            \
          (count) += c;                                                 \