Dynamically allocate the stack since SIGSTKSZ is not constant since glibc 2.34.

Backported from:

  https://github.com/openjdk/jdk17u/commit/bb7c412e259893091210267252faf3c0a1be0969

diff --git a/hotspot/test/runtime/StackGuardPages/exeinvoke.c b/hotspot/test/runtime/StackGuardPages/exeinvoke.c
--- a/hotspot/test/runtime/StackGuardPages/exeinvoke.c
+++ b/hotspot/test/runtime/StackGuardPages/exeinvoke.c
@@ -67,8 +67,17 @@ static void handler(int sig, siginfo_t *si, void *unused) {
   longjmp(context, 1);
 }
 
+static char* altstack = NULL;
+
 void set_signal_handler() {
-  static char altstack[SIGSTKSZ];
+  if (altstack == NULL) {
+    // Dynamically allocated in case SIGSTKSZ is not constant
+    altstack = malloc(SIGSTKSZ);
+    if (altstack == NULL) {
+      fprintf(stderr, "Test ERROR. Unable to malloc altstack space\n");
+      exit(7);
+    }
+  }
 
   stack_t ss = {
     .ss_size = SIGSTKSZ,