disable quiche_version, which is incompatible with gn

This temporarily disables the `quiche_version` method, since gn does not
support the `CARGO_PKG_VERSION` environment variable.

Change-Id: Ied060e70d4ccbcb3d05df8ca319d61d2ce0ecb78
diff --git a/src/ffi.rs b/src/ffi.rs
index 48d5946..272b934 100644
--- a/src/ffi.rs
+++ b/src/ffi.rs
@@ -38,11 +38,11 @@
 
 use crate::*;
 
-#[no_mangle]
-pub extern fn quiche_version() -> *const u8 {
-    static VERSION: &str = concat!(env!("CARGO_PKG_VERSION"), "\0");
-    VERSION.as_ptr()
-}
+// #[no_mangle]
+// pub extern fn quiche_version() -> *const u8 {
+//     static VERSION: &str = concat!(env!("CARGO_PKG_VERSION"), "\0");
+//     VERSION.as_ptr()
+// }
 
 struct Logger {
     cb: extern fn(line: *const u8, argp: *mut c_void),