Change to meaningful var names and take care of a compiler warning on IRIX 6.5.22 MIPSPro C 7.3 64bit

Place parenthesis surrounding macro parameters so that the use of sread and swrite is more intuitive.

Define NEED_MALLOC_H if including <stdlib.h> is not enough for proper compilation and <malloc.h> must also be included.

in libcurl as well, if necessary.

DNS cache must use the multi DNS cache if the easy handle's one is not using anyone in curl_multi_add_handle.

string comparisons on the path which is incorrect and provided a patch that
fixes this. I edited test case 8 to include details that test for this.

the crash was that libcurl internally was a bit confused about who owned the
DNS cache at all times so if you created an easy handle that uses a shared
DNS cache and added that to a multi handle it would crash. Now we keep more
careful internal track of exactly what kind of DNS cache each easy handle
uses: None, Private (allocated for and used only by this single handle),
Shared (points to a cache held by a shared object), Global (points to the
global cache) or Multi (points to the cache within the multi handle that is
automatically shared between all easy handles that are added with private
caches).

Finally get rid of CURL_CHECK_HEADERS_ONCE since it adds very little value and has portability issues.

Change some shell if...then...fi tests into case...esac tests which demand less resources.

Using backslashes and slashes in the strings of the sed 'y' command shall be avoided since its interpretation is not the same across platforms.

Now we use the sed 's' command with a bracket expression.

effect.