Add ODIN_NO_CRT global constant

core/runtime/procs.odin

@@ -24,6 +24,43 @@ when ODIN_ARCH == "wasm32" || ODIN_ARCH == "wasm64" {
 		}
 		return dst
 		
+	}
+} else when ODIN_NO_CRT {
+	@(link_name="memset")
+	memset :: proc "c" (ptr: rawptr, val: i32, len: int) -> rawptr {
+		if ptr != nil && len != 0 {
+			b := byte(val)
+			p := ([^]byte)(ptr)
+			for i in 0..<len {
+				p[i] = b
+			}
+		}
+		return ptr
+	}
+	
+	@(link_name="memmove")
+	memmove :: proc "c" (dst, src: rawptr, len: int) -> rawptr {
+		if dst != src {
+			d, s := ([^]byte)(dst), ([^]byte)(src)
+			d_end, s_end := d[len:], s[len:]
+			for i := len-1; i >= 0; i -= 1 {
+				d[i] = s[i]
+			}
+		}
+		return dst
+		
+	}
+	@(link_name="memcpy")
+	memcpy :: proc "c" (dst, src: rawptr, len: int) -> rawptr {
+		if dst != src {
+			d, s := ([^]byte)(dst), ([^]byte)(src)
+			d_end, s_end := d[len:], s[len:]
+			for i := len-1; i >= 0; i -= 1 {
+				d[i] = s[i]
+			}
+		}
+		return dst
+		
 	}
 } else {
 	memset :: proc "c" (ptr: rawptr, val: i32, len: int) -> rawptr {

core/runtime/procs_windows_amd64.odin

@@ -19,10 +19,12 @@ windows_trap_type_assertion :: proc "contextless" () -> ! {
 	windows_trap_array_bounds()
 }
 
-// @private
-// @(link_name="_tls_index")
-// _tls_index: u32;
+when ODIN_NO_CRT {
+	@private
+	@(link_name="_tls_index")
+	_tls_index: u32
 
-// @private
-// @(link_name="_fltused")
-// _fltused: i32 = 0x9875;
+	@private
+	@(link_name="_fltused")
+	_fltused: i32 = 0x9875
+}