Update samtools to support v1.3.1

Update the samtools package to support v1.3.1, which
- now uses configure script; and
- now depends on external htslib package.

The dependency on mpc seems to have been bogus, it's never linked in,
nor is it mentioned in the source tree.  I *do* have a version in
/usr/lib64, but ldd does not sure it being linked in either....

By depending on 'ncurses' I can do away with the need for the patch.

var/spack/repos/builtin/packages/samtools/package.py

@@ -25,18 +25,25 @@
 from spack import *
 
 class Samtools(Package):
-    """SAM Tools provide various utilities for manipulating alignments in the SAM format, 
-       including sorting, merging, indexing and generating
+    """SAM Tools provide various utilities for manipulating alignments in
+       the SAM format, including sorting, merging, indexing and generating
        alignments in a per-position format"""
 
     homepage = "www.htslib.org"
-    version('1.2','988ec4c3058a6ceda36503eebecd4122',url = "https://github.com/samtools/samtools/releases/download/1.2/samtools-1.2.tar.bz2")
+    url = "https://github.com/samtools/samtools/releases/download/1.3.1/samtools-1.3.1.tar.bz2"
 
-    depends_on("zlib")
-    depends_on("mpc")
-    parallel=False
-    patch("samtools1.2.patch",level=0)
+    version('1.3.1','a7471aa5a1eb7fc9cc4c6491d73c2d88')
+    version('1.2','988ec4c3058a6ceda36503eebecd4122')
+
+    depends_on("ncurses")
+    depends_on("htslib", when='@1.3.1') # htslib became standalone
+    depends_on('zlib', when='@1.2')     # needed for builtin htslib
 
     def install(self, spec, prefix):
-        make("prefix=%s" % prefix, "install")
-
+        if self.spec.version >= Version('1.3.1'):
+            configure('--prefix={0}'.format(prefix), '--with-ncurses')
+            make()
+            make('install')
+        else:
+            make("prefix=%s" % prefix)
+            make("prefix=%s" % prefix, "install")

var/spack/repos/builtin/packages/samtools/samtools1.2.patch

@@ -1,20 +0,0 @@
---- Makefile	2015-02-03 08:27:34.000000000 -0800
-+++ Makefile.new	2015-07-21 10:38:27.881406892 -0700
-@@ -26,7 +26,7 @@
- CFLAGS   = -g -Wall -O2
- LDFLAGS  =
- LDLIBS   =
--DFLAGS=     -D_FILE_OFFSET_BITS=64 -D_LARGEFILE64_SOURCE -D_CURSES_LIB=1
-+DFLAGS=     -D_FILE_OFFSET_BITS=64 -D_LARGEFILE64_SOURCE -D_CURSES_LIB=0
- LOBJS=      bam_aux.o bam.o bam_import.o sam.o \
-             sam_header.o bam_plbuf.o
- AOBJS=      bam_index.o bam_plcmd.o sam_view.o \
-@@ -37,7 +37,7 @@
-             faidx.o stats.o stats_isize.o bam_flags.o bam_split.o \
-             bam_tview.o bam_tview_curses.o bam_tview_html.o bam_lpileup.o
- INCLUDES=   -I. -I$(HTSDIR)
--LIBCURSES=  -lcurses # -lXCurses
-+#LIBCURSES=  -lcurses # -lXCurses
- 
- prefix      = /usr/local
- exec_prefix = $(prefix)