math/ocaml-zarith: Unbreak after ocaml-findlib change

Use the same technique madpilot used on x11-toolkits/ocaml-lablgtk2
to restore the build after the (unexpected) changed to the output
of ocamlfindlib during its update to 1.7.1

math/ocaml-zarith/Makefile

@@ -13,8 +13,6 @@ COMMENT=	OCaml arithmetic library for arbitrary precision integers
 LICENSE=	LGPL20
 LICENSE_FILE=	${WRKSRC}/LICENSE
 
-BROKEN=		does not build
-
 LIB_DEPENDS=	libgmp.so:math/gmp
 
 USES=			gmake perl5 shebangfix tar:tgz

math/ocaml-zarith/files/patch-configure

@@ -11,6 +11,15 @@
      IFS=':'
      for i in $PATH
      do
+@@ -258,7 +262,7 @@ searchbin ocamlfind
+ if test $? -eq 1 -a $ocamlfind != "no"; then 
+     instmeth='findlib'
+     if test "$installdir" = "auto"
+-    then installdir=`ocamlfind printconf destdir`; fi
++    then installdir=`ocamlfind printconf destdir | sed 's/:.*//'`; fi
+ else
+     searchbin install
+     if test $? -eq 1; then instmeth='install'
 @@ -304,6 +308,14 @@ case $host in
              arch='i686'
          fi