Fix ticket #2439: the FTS1 and FTS2 extensions use the non-standard,

Fix ticket #2439: the FTS1 and FTS2 extensions use the non-standard,
unportable and highly deprecated <malloc.h> header on all platforms
except Apple Mac OS X. The <malloc.h> actually is never required on
any OS with an at least partly POSIX-conforming API as the malloc(3) &
friends functions officially live in <stdlib.h> since over 10 years.
Under some platform like FreeBSD the inclusion of <malloc.h> since a few
years even causes an "#error" and this way a build failure. So, just get
rid of the bad <malloc.h> usage in FTS1 and FTS2 extensions at all and
stick with <stdlib.h> there only. (CVS 4191)

FossilOrigin-Name: 3f9a666143a8aafa0b1a5d56ec68f69f2b3d6a21