close options.h header after reading

Author: cconlon

src/wolfssl/_build_ffi.py

@@ -28,8 +28,10 @@
 
 # open <wolfssl/options.h> header to parse for #define's
 # This will throw a FileNotFoundError if not able to find options.h
-optionsHeader = wolfssl_inc_path() + "/wolfssl/options.h"
-optionsHeaderStr = open(optionsHeader, 'r').read()
+optionsHeaderPath = wolfssl_inc_path() + "/wolfssl/options.h"
+optionsHeader = open(optionsHeaderPath, 'r')
+optionsHeaderStr = optionsHeader.read()
+optionsHeader.close()
 
 # require HAVE_SNI (--enable-sni) in native lib
 if '#define HAVE_SNI' not in optionsHeaderStr: