[m-rev.] for review: Only assume structure assignment conflicts with global registers on x86.

[Peter Wang]

configure.ac:
    As above. The result of the "structure assignment conflicts with
    global registers" test was hard coded to fail on gcc >= 3, but the
    issue it avoids possibly only occurs on x86. I cannot reproduce it
    on x86-64 (with gcc 8.3.0) but I *can* reproduce it on x86.

diff --git a/configure.ac b/configure.ac
index 10b4f8d79..78f66896a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -4070,7 +4070,7 @@ AC_TRY_RUN(
 
         int main() {
             spied_procs[1] = spied_procs[0];
-        #if __GNUC__ >= 3
+        #if (__GNUC__ >= 3) && defined(__i386__)
             /* gcc 3.1 seems to have problems with structure assignment
                and global registers, but which this simple test case
                does not trigger. So just force the test to fail for gcc 3.x. */
-- 
2.28.0