python-pycurl: Fix building

Add python to DEPENDS and ensure the required environment variables are
available at build time.

Signed-off-by: Joshua Lock <josh@linux.intel.com>

meta/packages/python/python-pycurl_7.19.0.bb

@@ -2,7 +2,7 @@ DESCRIPTION = "libcurl Python Bindings"
 SECTION = "devel/python"
 PRIORITY = "optional"
 LICENSE = "LGPL"
-DEPENDS = "curl"
+DEPENDS = "curl python"
 SRCNAME = "pycurl"
 PR = "r0"
 
@@ -17,6 +17,8 @@ inherit distutils
 # need to export these variables for python-config to work
 export BUILD_SYS
 export HOST_SYS
+export STAGING_INCDIR
+export STAGING_LIBDIR
 
 RDEPENDS = "python-core curl"