[patch] const_cast to be replaced by str_unconst

[Roland Illig]

Pavel Tsekov wrote:
>>For those of you that are concerned about the performance loss of an
>>extra function call: It is much more important for the code to be
>>readable and checkable by the compiler than to be 1 millisecond faster
>>at all.
> 
> You can inline it.

When compiling with gcc using -Wcast-qual, this would give us a warning 
for every file. The non-inlined version would produce the warning only 
for one file, namely src/util.c.

I want as few warnings as possible.

Roland