Add Python support to gdb. (#1790)

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

@@ -41,9 +41,18 @@ class Gdb(Package):
     version('7.9', '8f8ced422fe462a00e0135a643544f17')
     version('7.8.2', '8b0ea8b3559d3d90b3ff4952f0aeafbc')
 
+    variant('python', default=True, description='Compile with Python support')
+
+    # Required dependency
     depends_on('texinfo', type='build')
 
+    # Optional dependency
+    depends_on('python', when='+python')
+
     def install(self, spec, prefix):
-        configure('--prefix=%s' % prefix)
+        options = ['--prefix=%s' % prefix]
+        if '+python' in spec:
+            options.extend(['--with-python'])
+        configure(*options)
         make()
         make("install")