Upgrade rust/crates/regex to 1.5.4

Test: make
Change-Id: I0eab39246dc2aea41a62c15661e350b490f06c1d
diff --git a/src/re_builder.rs b/src/re_builder.rs
index fc140f8..ee63836 100644
--- a/src/re_builder.rs
+++ b/src/re_builder.rs
@@ -37,10 +37,10 @@
     ($name:ident, $regex_mod:ident, $only_utf8:expr) => {
         pub mod $name {
             use super::RegexOptions;
-            use error::Error;
-            use exec::ExecBuilder;
+            use crate::error::Error;
+            use crate::exec::ExecBuilder;
 
-            use $regex_mod::Regex;
+            use crate::$regex_mod::Regex;
 
             /// A configurable builder for a regular expression.
             ///
@@ -235,10 +235,10 @@
     ($name:ident, $regex_mod:ident, $only_utf8:expr) => {
         pub mod $name {
             use super::RegexOptions;
-            use error::Error;
-            use exec::ExecBuilder;
+            use crate::error::Error;
+            use crate::exec::ExecBuilder;
 
-            use re_set::$regex_mod::RegexSet;
+            use crate::re_set::$regex_mod::RegexSet;
 
             /// A configurable builder for a set of regular expressions.
             ///