gnuplot : modifications to build on RHLE 6

var/spack/packages/fontconfig/package.py

@@ -8,9 +8,10 @@ class Fontconfig(Package):
     version('2.11.1' , 'e75e303b4f7756c2b16203a57ac87eba')
 
     depends_on('freetype')
+    depends_on('libxml2')
 
     def install(self, spec, prefix):
-        configure("--prefix=%s" % prefix)
+        configure("--prefix=%s" % prefix, "--enable-libxml2")
 
         make()
         make("install")

var/spack/packages/gnuplot/package.py

@@ -45,7 +45,9 @@ class Gnuplot(Package):
     depends_on('libgd')
     depends_on('cairo')
     depends_on('pango')
-    depends_on('wx')
+    depends_on('wx', when='+wx')
+
+    variant('wx', default=False, description='Activates wxWidgets terminal')
 
     def install(self, spec, prefix):
         # It seems there's an open bug for wxWidgets support

var/spack/packages/libgd/package.py

@@ -39,6 +39,8 @@ class Libgd(Package):
 
     version('2.1.1', 'e91a1a99903e460e7ba00a794e72cc1e')
 
+    depends_on('libpng')
+
     def install(self, spec, prefix):
 
         with working_dir('spack-build', create=True):