rust-themis: Run the skipped tests on the 32bit

They were skipped because allocation on 32-bit platforms failed
while trying to allocate something bigger than 2GB. This is due to
usage of `.reserve` which panics if it couldn't fulfill the request.

Since we traversed to the rust 1.58, we now have the `try_*` methods,
including the `.try_reserve` which allows us handle panics gracefully.

I've tested it manually on pi4 and it works!

Author: G1gg1L3s

tests/rust/secure_cell.rs

@@ -760,11 +760,6 @@ mod token_protect {
     }
 
     #[test]
-    // FIXME(ilammy, 2020-05-25): avoid capacity allocation panics (T1649)
-    // This tests panics on 32-bit architectures due to size overflow.
-    // The implementation needs to use Vec::try_reserve instead of Vec::reserve
-    // when it becomes available in stable Rust.
-    #[cfg_attr(target_pointer_width = "32", ignore)]
     fn detects_corrupted_token() {
         let cell = SecureCell::with_key(SymmetricKey::new())
             .unwrap()
@@ -817,11 +812,6 @@ mod token_protect {
     }
 
     #[test]
-    // FIXME(ilammy, 2020-05-25): avoid capacity allocation panics (T1649)
-    // This tests panics on 32-bit architectures due to size overflow.
-    // The implementation needs to use Vec::try_reserve instead of Vec::reserve
-    // when it becomes available in stable Rust.
-    #[cfg_attr(target_pointer_width = "32", ignore)]
     fn detects_data_token_swap() {
         let cell = SecureCell::with_key(SymmetricKey::new())
             .unwrap()