configure: check if compiler halts on function prototype mismatch
setup_once.h: HP-UX specific 'bool', 'false' and 'true' definitions.

Also reverts commit f254c59dc7
curl-functions.m4: improve gethostname arg 2 data type check
VC6 IDE: link with advapi32.lib when using WIN32 crypto API (md5.c)
configure.ac: clear local test intended variables before use
libntlmconnect.c: fix compiler warnings and OOM handling
bundles connection caching: some out of memory handling fixes
configure: add minimal sanity check on user provided CFLAGS and CPPFLAGS
configure: LIBMETALINK_CFLAGS actually is LIBMETALINK_CPPFLAGS
SCP: relative path didn't work

When prefixing a path with /~/ it is supposed to be used relative to the
user's home directory but it didn't work. Now we cut off the entire
three byte sequenct "/~/" which seems to be how OpenSSH does it.

Bug: http://curl.haxx.se/bug/view.cgi?id=1173
Reported by: Balaji Parasuram
configure: add internal sanity check (warn only) on vars for makefiles
lib543.c: OOM handling fixes
multi.c: OOM handling fix
runtests.pl: prepend $srcdir to HTTPTLS server config files path
curl_multi_wait: avoid an unnecessary memory allocation
curl_multi_wait: OOM handling fix
test 1502: OOM handling fixes
test 1503: same as 1502 but with a different cleanup sequence
pop3_doing: don't call pop3_dophase_done() if already failed

... it also clobbered the 'result' return value so that it wouldn't
return the error back to the parent function properly, which broke test
809 when run with 'multi-always'.
Curl_conncache_foreach: allow callback to break loop

... and have it take a proper 'struct connectdata *' as first argument