Warnings in r1403

Found with "CFLAGS='-W -Wall -padantic'". I've removed all the "unused var", "comparison of signed and unsigned", "printf format wrong" and a few other warnings.

ikarus-fasl.c:292: warning: pointer of type ‘void *’ used in arithmetic

Due to "(void*)(long)x + y", I think this should be "(void*)((long)x + y)". Could be very serious.

ikarus-collect.c:1047: warning: comparison of unsigned expression >= 0 is always true
ikarus-collect.c:1657: warning: comparison of unsigned expression >= 0 is always true

Due to "unsigned int x; ... assert(x >= 0)" (I'm on the fence about whether this is a problem.)

ikarus-main.c:43: warning: string length ‘960’ is greater than the length ‘509’ ISO C89 compilers are required to support

Due to the help/usage message you could split it into multiple strings but probably not a problem.

ikarus-runtime.c:988: warning: ISO C does not allow extra ‘;’ outside of a function

Due to "void foo(...) { ... } ;" should be "void foo(...) { ... }". Trivial but an easy fix.