[gcc(refs/vendors/riscv/heads/gcc-15-with-riscv-opts)] RISC-V: Fix uninit riscv_subset_list::m_allow_adding_dup issue

[Jeff Law]

https://gcc.gnu.org/g:475abd8e7927022d950d0eb3be1135c8a67f3f1a

commit 475abd8e7927022d950d0eb3be1135c8a67f3f1a
Author: Kito Cheng <kito.cheng@sifive.com>
Date:   Tue May 13 10:34:34 2025 +0800

    RISC-V: Fix uninit riscv_subset_list::m_allow_adding_dup issue
    
    We forgot to initialize m_allow_adding_dup in the constructor of
    riscv_subset_list, then that will be a random value...that will lead
    to a random behavior of the -march may accpet duplicate extension.
    
    gcc/ChangeLog:
    
            * common/config/riscv/riscv-common.cc
            (riscv_subset_list::riscv_subset_list): Init m_allow_adding_dup.
    Reviewed-by: Christoph Müllner <christoph.muellner@vrull.eu>
    
    (cherry picked from commit 991adf8b18c3fa03eff6cfbf396d9a15ef17f93c)

Diff:
---
 gcc/common/config/riscv/riscv-common.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/gcc/common/config/riscv/riscv-common.cc b/gcc/common/config/riscv/riscv-common.cc
index 3d3ca110699b..53ca03910b38 100644
--- a/gcc/common/config/riscv/riscv-common.cc
+++ b/gcc/common/config/riscv/riscv-common.cc
@@ -364,7 +364,7 @@ riscv_subset_t::riscv_subset_t ()
 
 riscv_subset_list::riscv_subset_list (const char *arch, location_t loc)
   : m_arch (arch), m_loc (loc), m_head (NULL), m_tail (NULL), m_xlen (0),
-    m_subset_num (0)
+    m_subset_num (0), m_allow_adding_dup (false)
 {
 }