security/samhain: don't use sbrk

Samhain has an internal malloc implementation that uses sbrk and malloc.
There's a fallback during initialization if sbrk fails so replace sbrk
calls with a function that return the failure value ((void *)-1).

PR:		275646
Approved by:	freebsd@gregv.net (maintainer)

security/samhain/Makefile

@@ -14,7 +14,7 @@ LICENSE=	GPLv2
 BROKEN_mips=		fails to configure: error: Could not find the libwrap library
 BROKEN_mips64=		fails to configure: error: Could not find the libwrap library
 
-USES=			sbrk shebangfix
+USES=			shebangfix
 SHEBANG_FILES=		scripts/samhainadmin-gpg.pl.in \
 			scripts/samhainadmin-sig.pl.in
 

security/samhain/files/patch-src_dnmalloc.c

@@ -0,0 +1,21 @@
+--- src/dnmalloc.c.orig
++++ src/dnmalloc.c
+@@ -660,8 +660,18 @@
+   sample version for pre-OSX macos.
+ */
+ 
++#ifdef __FreeBSD__
++static void *nosbrk(ptrdiff_t len __unused) {
++  return MORECORE_FAILURE;
++}
++#endif
++
+ #ifndef MORECORE
++#ifdef __FreeBSD__
++#define MORECORE nosbrk
++#else
+ #define MORECORE sbrk
++#endif
+ #endif
+ 
+