python-pycurl: remove unnecessary exports

These variables are exported through distutils.bbclass, so there's no need to do
it again.

(From OE-Core rev: 247522b0eae6ec528350888d2283e84bb1e250fa)

Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-devtools/python/python-pycurl_7.21.5.bb

@@ -21,12 +21,6 @@ S = "${WORKDIR}/${SRCNAME}-${PV}"
 
 inherit distutils
 
-# need to export these variables for python-config to work
-export BUILD_SYS
-export HOST_SYS
-export STAGING_INCDIR
-export STAGING_LIBDIR
-
 BBCLASSEXTEND = "native"
 
 # Ensure the docstrings are generated as make clean will remove them