Add rust bpf allocator (#4426)

sdk/bpf/rust-utils/src/alloc.rs

@@ -0,0 +1,23 @@
+//! @brief Solana Rust-based BPF program memory allocator shim
+
+use crate::log::*;
+use core::alloc::{GlobalAlloc, Layout};
+
+pub struct Allocator;
+unsafe impl GlobalAlloc for Allocator {
+    unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
+        sol_alloc_free_(layout.size() as u64, 0)
+    }
+    unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) {
+        sol_alloc_free_(layout.size() as u64, ptr as u64);
+    }
+}
+extern "C" {
+    fn sol_alloc_free_(size: u64, ptr: u64) -> *mut u8;
+}
+
+#[alloc_error_handler]
+fn my_alloc_error_handler(_: core::alloc::Layout) -> ! {
+    sol_log("alloc_error_handler");
+    panic!();
+}