package/python-sip: fix install with python 3.8

Install python-sip in the correct directory otherwise build of
python-pyqt5 will fail

Fixes:
 - http://autobuild.buildroot.org/results/a471b33e8a9803dfe8b36e83647c98165873ddf1

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/python-sip/python-sip.mk

@@ -21,7 +21,7 @@ else ifeq ($(BR2_PACKAGE_PYTHON3),y)
 PYTHON_SIP_DEPENDENCIES += python3
 HOST_PYTHON_SIP_DEPENDENCIES += host-python3
 PYTHON_SIP_LIB_DIR = usr/lib/python$(PYTHON3_VERSION_MAJOR)/site-packages
-PYTHON_SIP_INCLUDE_DIR = usr/include/python$(PYTHON3_VERSION_MAJOR)m
+PYTHON_SIP_INCLUDE_DIR = usr/include/python$(PYTHON3_VERSION_MAJOR)
 endif
 
 define HOST_PYTHON_SIP_CONFIGURE_CMDS