tools: new tool to extracts function names declared in V files

vlib/hash/hash.v

@@ -4,7 +4,7 @@
 
 module hash
 
-interface Hash {
+interface Hasher {
 	// Sum appends the current hash to b and returns the resulting array.
 	// It does not change the underlying hash state.
 	sum(b []byte) []byte
@@ -12,10 +12,10 @@ interface Hash {
 	block_size() int
 }
 
-interface Hash32 {
+interface Hash32er {
 	sum32() u32
 }
 
-interface Hash64 {
+interface Hash64er {
 	sum64() u64
 }