RFR (L): 8062370: Various minor code improvements

[Lindenmaier, Goetz]

Hi,

this change contains a row of minor code improvements we did to fulfil
our internal quality requirements.  We would like to share these with
openJDK.

Please review and test this change.  I please need a sponsor.
http://cr.openjdk.java.net/~goetz/webrevs/8062370/webrev.00/
https://bugs.openjdk.java.net/browse/JDK-8062370

We tested this on windows 64, linux x86_64, mac, solaris sparc 32+64 bit and,
of course, the ppc platforms.


Some details:

CONST64(0x8000000000000000) is wrong, as 0x8... is positive, and thus not representable as i64 what is used in the CONST64 macro. This change adapts UCONST64 to use ui64, and the usages of these macros where necessary.

We add some more strncpy uses.  Also, we fix strncpy on windows.  There, strncpy does not write a \0 into the last byte if the copied string is too long.

We add some missing memory frees and some closing of files.

jio_vsnprintf() works differently on windows and linux. This change adapts this to show the same behaviour on all platforms. See java.cpp.

Best regards,

  Goetz