Explicit cast in JS_NewInt64 & JS_NewUint32

This avoids the two GCC -Wconversion warnings in this public header, which is useful when using extensive error reporting from the compiler, and treating warnings as errors.

quickjs.h

@@ -501,9 +501,9 @@ static js_force_inline JSValue JS_NewInt64(JSContext *ctx, int64_t val)
 {
     JSValue v;
     if (val >= INT32_MIN && val <= INT32_MAX) {
-        v = JS_NewInt32(ctx, val);
+        v = JS_NewInt32(ctx, (int32_t)val);
     } else {
-        v = JS_NewFloat64(ctx, val);
+        v = JS_NewFloat64(ctx, (double)val);
     }
     return v;
 }
@@ -512,9 +512,9 @@ static js_force_inline JSValue JS_NewUint32(JSContext *ctx, uint32_t val)
 {
     JSValue v;
     if (val <= 0x7fffffff) {
-        v = JS_NewInt32(ctx, val);
+        v = JS_NewInt32(ctx, (int32_t)val);
     } else {
-        v = JS_NewFloat64(ctx, val);
+        v = JS_NewFloat64(ctx, (double)val);
     }
     return v;
 }