chore: fix Make script when failed

[thinkerou]

before:

# github.com/gin-gonic/gin
/tmp/go-build038919107/github.com/gin-gonic/gin/_test/_obj_test/context.go:719:11: unknown field 'SameSite' in struct literal of type http.Cookie
FAIL	github.com/gin-gonic/gin [build failed]
The command "make test" exited with 0.

And

# github.com/gin-gonic/gin/render
package github.com/gin-gonic/gin/render (test)
	imports github.com/stretchr/testify/assert
	imports github.com/pmezard/go-difflib/difflib: cannot find package "github.com/pmezard/go-difflib/difflib" in any of:
	/home/travis/gopath/src/github.com/gin-gonic/gin/vendor/github.com/pmezard/go-difflib/difflib (vendor tree)
	/home/travis/.gimme/versions/go1.8.7.linux.amd64/src/github.com/pmezard/go-difflib/difflib (from $GOROOT)
	/home/travis/gopath/src/github.com/pmezard/go-difflib/difflib (from $GOPATH)
FAIL	github.com/gin-gonic/gin/render [setup failed]

when test case failed, it should return 1 not 0.

For example #1615

[codecov]

Codecov Report

Merging #1774 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1774   +/-   ##
=======================================
  Coverage   98.48%   98.48%           
=======================================
  Files          41       41           
  Lines        2046     2046           
=======================================
  Hits         2015     2015           
  Misses         19       19           
  Partials       12       12

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