Use system wcslib

Patch written by Kacper Kowalik <xarthisius@gentoo.org>

--- a/setup.py
+++ b/setup.py
@@ -3,7 +3,8 @@
 from kapteyn import __version__ as version
 from glob import glob
 import sys, os
-
+from subprocess import Popen, PIPE
+from re import match
 try:
    import numpy
 except:
@@ -14,21 +15,27 @@
 '''
    sys.exit(1)
 
-try:
-   wcslib_dir = glob('src/wcslib*/C/')[0]
-except:
-   print '''
--- Error.
-Unable to find WCSLIB source distribution.
-'''
-   sys.exit(1)
+def pkgconfig(*packages, **kw):
+    flag_map = {'-I': 'include_dirs', '-L': 'library_dirs', '-l': 'libraries'}
+    arg = "--libs --cflags --modversion %s" % ' '.join(packages) 
+    for tok in Popen(["pkg-config "+ arg],stdout=PIPE, shell=True).communicate()[0].split():
+       token = tok.decode("utf-8")
+       if(match("[0-9]",token)):
+          kw.setdefault("version",[]).append(token)
+       else:
+          kw.setdefault(flag_map.get(token[:2]), []).append(token[2:])
+    return kw
 
 include_dirs = []
 numdir = os.path.dirname(numpy.__file__)
 ipath = os.path.join(numdir, numpy.get_include())
 include_dirs.append(ipath)
 include_dirs.append('src')
-include_dirs.append(wcslib_dir)
+
+WCSLIB = pkgconfig('wcslib')
+WCSVERSION = Popen(["pkg-config --modversion"],stdout=PIPE, shell=True).communicate()[0].split()
+
+include_dirs += WCSLIB['include_dirs']
 
 short_descr = "Kapteyn Package: Python modules for astronomical applications"
 
@@ -94,27 +101,6 @@
    "xyz.c"
 ]
 
-wcslib_src = [
-   "cel.c",
-   "lin.c",
-   "log.c",
-   "prj.c",
-   "spc.c",
-   "sph.c",
-   "spx.c",
-   "tab.c",
-   "wcs.c",
-   "wcsfix.c",
-   "wcshdr.c",
-   "wcsprintf.c",
-   "wcstrig.c",
-   "wcsunits.c",
-   "wcsutil.c",
-   "wcserr.c",
-   "flexed/wcsulex.c",
-   "flexed/wcsutrn.c"
-]
-
 ndimg_src = [
    "nd_image.c",
    "ni_filters.c",
@@ -125,8 +111,7 @@
    "ni_support.c",
 ]
 
-wcs_src       = (   ['src/'        + source for source in wcsmod_src]
-                  + [wcslib_dir    + source for source in wcslib_src]  )
+wcs_src       = ( ['src/'        + source for source in wcsmod_src] )
 
 _nd_image_src = ['src/ndimg/'  + source for source in ndimg_src]
 
@@ -168,7 +153,8 @@
       Extension(
          "wcs", wcs_src,
           include_dirs=include_dirs,
-          define_macros=define_macros
+          define_macros=define_macros,
+          libraries=WCSLIB['libraries']
       ),
       Extension(
          "ascarray",