optimize detect import blocks

[daixiang0]

• optimize import blocks detection logic
• introduce breaking change: remove isolated comments

Signed-off-by: Loong loong.dai@intel.com

[daixiang0]

Fix #119

[avorima]

When I run this PR on the example repo of #119 (https://gitlab.com/cznic/sortutil.git) I get the following diff:

iff --git a/sortutil.go b/sortutil.go
index 28ed235..210ba49 100644
--- a/sortutil.go
+++ b/sortutil.go
@@ -4,7 +4,7 @@

 // Package sortutil provides utilities supplementing the standard 'sort' package.
 //
-// Changelog
+// # Changelog
 //
 // 2019-10-24: v1.1.0: Added topological sort.
 //
@@ -13,11 +13,9 @@ package sortutil // import "modernc.org/sortutil"

 import (
        "math/big"
+       "sort"
 )

-import "sort"
-
-// BigIntSlice attaches the methods of sort.Interface to []*big.Int, sorting in increasing order.
 type BigIntSlice []*big.Int

 func (s BigIntSlice) Len() int           { return len(s) }

I don't think the comment of BigIntSlice should be removed and that # also looks suspicious.

[daixiang0]

@avorima which version do you use?

[avorima]

I tested with version 0.8.3, but it looks like the latest version 0.9.0 no longer has any issues with the example

[daixiang0]

Thanks, let's use the latest version.