Ignore more unimportant files.

- Emacs backup files.
- *.orig files left by hg merge conflicts.
- core files.
- generated enam.c files.
- runtime.acid now has an architecture.

R=rsc
http://go/go-review/1026017

.hgignore

@@ -6,18 +6,21 @@ syntax:glob
 ._*
 .nfs.*
 [568a].out
+*~
+*.orig
+core
 _obj
 _test
 src/cmd/6a/6a
 y.tab.[ch]
-src/cmd/6l/enam.c
+src/cmd/?l/enam.c
 src/cmd/gc/builtin.c
 src/cmd/gc/mkbuiltin1
 src/cmd/gc/opnames.h
 src/pkg/exp/ogle/ogle
 src/pkg/runtime/cgo2c
 src/pkg/runtime/*/asm.h
-src/pkg/runtime/runtime.acid
+src/pkg/runtime/runtime.acid.*
 test/pass.out
 test/run.out
 test/times.out
@@ -25,3 +28,4 @@ test/times.out
 syntax:regexp
 ^pkg/
 ^src/cmd/(.*)/6?\1$
+^.*/core.[0-9]*$