searcher: always strip BOM

This fixes a bug where a BOM prefix was included. While this was somewhat
intentional in order to have a faithful "UTF8 passthru" option, in
practice, this causes problems such as breaking patterns like `^` in a
really non-obvious way.

The actual fix was to add a new API to encoding_rs_io, which this commit
brings in.

Fixes #1163

grep-searcher/Cargo.toml

@@ -15,7 +15,7 @@ license = "Unlicense/MIT"
 [dependencies]
 bytecount = "0.5"
 encoding_rs = "0.8.14"
-encoding_rs_io = "0.1.3"
+encoding_rs_io = "0.1.4"
 grep-matcher = { version = "0.1.1", path = "../grep-matcher" }
 log = "0.4.5"
 memchr = "2.1"

grep-searcher/src/searcher/mod.rs

@@ -307,6 +307,7 @@ impl SearcherBuilder {
         decode_builder
             .encoding(self.config.encoding.as_ref().map(|e| e.0))
             .utf8_passthru(true)
+            .strip_bom(true)
             .bom_override(true);
         Searcher {
             config: config,