Gccgo on non Linux platforms (where -fsplit-stack isn't supported) cannot resize
stack during the runtime resulting in segfaults when running deeper recursion.

This patch allows setting higher min stack size, which can in some cases resolve
these issues (although it might also cause memory exhaustion in highly multi
threaded programs).

This was reported upstream:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107491

--- gcc-12.2.0/libgo/runtime/proc.c
+++ gcc-12.2.0/libgo/runtime/proc.c
@@ -57,6 +57,16 @@
 # define StackMin ((sizeof(char *) < 8) ? 2 * 1024 * 1024 : 4 * 1024 * 1024)
 #endif
 
+static uintptr minstacksize;
+
+void runtime_setminstacksize(int32)
+  __asm__(GOSYM_PREFIX "runtime.setminstacksize");
+
+void runtime_setminstacksize(int32 size)
+{
+	minstacksize = (uintptr)size * 1024 * 1024;
+}
+
 uintptr runtime_stacks_sys;
 
 void gtraceback(G*)
@@ -803,6 +813,9 @@
 	newg = allocg();
 	if(allocatestack) {
 		stacksize = StackMin;
+		if (stacksize < minstacksize) {
+			stacksize = minstacksize;
+		}
 		if(signalstack) {
 			stacksize = 32 * 1024; // OS X wants >= 8K, GNU/Linux >= 2K
 #ifdef SIGSTKSZ
--- gcc-12.2.0/libgo/go/runtime/runtime1.go
+++ gcc-12.2.0/libgo/go/runtime/runtime1.go
@@ -22,6 +22,8 @@ import (
 //go:linkname parsedebugvars
 //go:linkname timediv
 
+func setminstacksize(size int32)
+
 // Keep a cached value to make gotraceback fast,
 // since we call it on every call to gentraceback.
 // The cached value is a uint32 in which the low bits
@@ -335,6 +337,7 @@ var debug struct {
 	allocfreetrace int32
 	inittrace      int32
 	sbrk           int32
+	minstacksize   int32
 }
 
 var dbgvars = []dbgVar{
@@ -357,6 +360,7 @@ var dbgvars = []dbgVar{
 	{"asyncpreemptoff", &debug.asyncpreemptoff},
 	{"inittrace", &debug.inittrace},
 	{"harddecommit", &debug.harddecommit},
+	{"minstacksize", &debug.minstacksize},
 }
 
 func parsedebugvars() {
@@ -417,6 +421,8 @@ func parsedebugvars() {
 
 	setTraceback(gogetenv("GOTRACEBACK"))
 	traceback_env = traceback_cache
+
+	setminstacksize(debug.minstacksize)
 }
 
 //go:linkname setTraceback runtime_1debug.SetTraceback