syntax: fix compilation errors with unicode-perl

When only the unicode-perl feature is enabled, regex-syntax would fail
to build. It turns out that 'cargo fix' doesn't actually fix all
imports. It looks like it only fixes things that it can build in the
current configuration.

Fixes #769, Fixes #770

regex-syntax/src/unicode.rs

@@ -348,7 +348,7 @@ pub fn perl_space() -> Result<hir::ClassUnicode> {
 
     #[cfg(all(feature = "unicode-perl", not(feature = "unicode-bool")))]
     fn imp() -> Result<hir::ClassUnicode> {
-        use unicode_tables::perl_space::WHITE_SPACE;
+        use crate::unicode_tables::perl_space::WHITE_SPACE;
         Ok(hir_class(WHITE_SPACE))
     }
 
@@ -372,7 +372,7 @@ pub fn perl_digit() -> Result<hir::ClassUnicode> {
 
     #[cfg(all(feature = "unicode-perl", not(feature = "unicode-gencat")))]
     fn imp() -> Result<hir::ClassUnicode> {
-        use unicode_tables::perl_decimal::DECIMAL_NUMBER;
+        use crate::unicode_tables::perl_decimal::DECIMAL_NUMBER;
         Ok(hir_class(DECIMAL_NUMBER))
     }