base_c: fixed implementation of atomic store to ensure sequential consistency

base_c/src/atomicfunc_32.asm

@@ -114,7 +114,7 @@ define_or_assign @embb_internal__atomic_or_assign_1_asm@8, byte, dl
 define_store macro name, size, value
 define_store macro name, size, value
 	public name
 	public name
 	name proc
 	name proc
-		mov size ptr [ecx], value
+		xchg size ptr [ecx], value
 		ret
 		ret
 	name endp
 	name endp
 endm
 endm

base_c/src/atomicfunc_64.asm

@@ -107,7 +107,7 @@ define_or_assign embb_internal__atomic_or_assign_1_asm, byte, dl
 define_store macro name, size, value
 define_store macro name, size, value
 	public name
 	public name
 	name proc
 	name proc
-		mov size ptr [rcx], value
+		xchg size ptr [rcx], value
 		ret
 		ret
 	name endp
 	name endp
 endm
 endm