plscheme - plscheme: Add a "#ifndef CACHE_MAX_SIZE" check into

Log Message:
-----------
Add a "#ifndef CACHE_MAX_SIZE" check into plscheme.c and a missing
CACHE_MAX_SIZE definition to compile command in README.plscheme.

Modified Files:
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plscheme:
README.plscheme (r1.7 -> r1.8)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/plscheme/plscheme/README.plscheme.diff?r1=1.7&r2=1.8)
plscheme.c (r1.20 -> r1.21)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/plscheme/plscheme/plscheme.c.diff?r1=1.20&r2=1.21)