Fix unintended assignement

Found by coverity
Fix a comparison between unsigned int and zero

Found by coverity
Fix parameter to Remove_Series

The "n" to Remove_Series should be the number of elements to be removed
from the series, not the size of the element in bytes, as the width of
the series is sizeof(REBSER *) (See Init_Memory in m-gc.c)

It should only remove the series in question.
Promote integer type in overflow detection

without promotion, *sum is i32, and will always be within the range of
[MIN_I32, MAX_I32]
Add a coverity annotation
Add missing va_end

Found by coverity
Add missing va_end

Found by coverity
Fix unmatched if statements

The actual nested level doesn't go with the intention.

Found by coverity
Fix regressions
Fix regressions

"even? 0:0:0" will cause an error
Check return value from fcntl

Complained by coverity
Add asserts to prevent coverity from complaining
Remove dead code

Complained by coverity
Check pointer before dereferencing it

complained by coverity
Fix indentation

This is confusing, and coverity complains about it.
Fix a potential integer overflow

multiplication of two 32-bit integers will yield a 32-bit integer, and
that could overflow, even though it's gonna be stored in a 64-bit
integer. The overflow happens before widening.
Fix integer overflow

This fix the problem:
>> make time! [596524000 0 0]
== 764:26:40
>> to integer! 764:26:40
== 2752000

Found by coverity
Fix build on windows
Add some asserts to shut off coverity
Check return value from ftell

It could return a negative value, which can't be used in later call.

Complained by coverity.