Polkavm heap (#2)

Use PolkaVM heap

crates/pallet-contracts-pvm-llapi/src/polkavm_guest.c

@@ -21,6 +21,16 @@ void * memcpy(void *dst, const void *_src, size_t len) {
     return dst;
 }
 
+void *  __sbrk(uint32_t size) {
+    uint32_t address;
+    __asm__ __volatile__(
+            ".insn r 0xb, 1, 0, %[dst], %[sz], zero"
+            : [dst] "=r" (address)
+            : [sz] "ir" (size)
+            :
+    );
+    return (void *)address;
+}
 
 // Exports
 

crates/pallet-contracts-pvm-llapi/src/polkavm_guest.h

@@ -162,4 +162,3 @@ static void __attribute__ ((naked, used)) POLKAVM_UNIQUE(polkavm_stack_size)() {
 }
 
 #endif
-