Fix actions (#1)

* Try fixing ci

* Fixed invalid flag

* Add flag for LDFLAGS

.github/workflows/ci.yml

@@ -7,12 +7,15 @@ on: [push, pull_request]
 jobs:
   build:
     runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        go: [ '1.15', '1.14', '1.13' ]
     steps:
       - uses: actions/checkout@v2
       - name: "Setup Golang"
         uses: actions/setup-go@v2
         with:
-          go-version: 1.15
+          go-version: ${{ matrix.go }}
       # https://github.com/actions/cache/blob/master/examples.md#go---modules
       - name: "Cache Go Modules"
         id: cache

bloomfilter.go

@@ -1,6 +1,7 @@
 package bloomfilter
 
 // #cgo CFLAGS: -Wall
+// #cgo LDFLAGS: -lm
 // #include<math.h>
 import "C"
 import (