Close the Readline init file after use
Close the Readline init file after use

Although it was eligible for garbage collection, until that point
forking would leak the file descriptor.

Tested-by: Mark Somerville <26cc3217be640e8220112c25628da6e11c78db95@pccl.info> [F17, MRI 1.9.3/2.0.0-preview1]
Signed-off-by: Mark Somerville <f1b5a91d4d6ad523f2610114591c007e75d15084@scottishclimbs.com>

rapid7/rb-readline,ConnorAtherton/rb-readline,abinoam/rb-readline