global: fix when local and global has same id

In the second pass, local var with same name as global var was always
considerated as global. Not anymore.

 * transform/global2.go : Here.
1 job for hm/global in 1 minute and 49 seconds
Status Job ID Name Coverage
failed #128817


Name Stage Failure
debian-stable-gcc Test
PASS: passes/select.go
PASS: passes/slices.go
PASS: passes/struct.go
PASS: passes/switch.go
PASS: passes/variablename.go
2 errors found!
make: *** [Makefile:39: check] Error 1
Cleaning up file based variables
ERROR: Job failed: exit code 1