sip3: Fix segmentation fault

The first version of this patch introduced a problem with python3-pyqt5.
Python emitted the following error message when one attempted to import
PyQt5.Qt:

  ImportError: dynamic module does not define module export function (PyInit_Qt)

This came about due to segfault in sip when executed in do_configure of
python3-pyqt5.  This resulted in a zero-length sipQtcmodule.c file being
produced.  This compiled successfully which meant no build failure was
observed.

The segfault was caused by a mistake in backporting the patch from SIP 6.
The generateCompositeCpp() function uses the generate_include_sip_h()
helper function in later versions which doesn't exist in SIP 4.

We must replace the first parameter passed to isPY_SSIZE_T_CLEAN() from
mod to pt->module to account for this. The change is not necessary for
generateInternalAPIHeader()

To simplify the patch we can remove the generated lexer and parser files
and run flex and bison in do_configure instead.

Signed-off-by: Rob Woolley <rob.woolley@windriver.com>
Tested-by: Toby Flynn <campingandskiing@gmail.com>
Signed-off-by: Armin Kuster <akuster808@gmail.com>

meta-oe/recipes-devtools/sip/sip3_4.19.23.bb

@@ -15,7 +15,7 @@ inherit python3-dir python3native
 
 S = "${WORKDIR}/sip-${PV}"
 
-DEPENDS = "python3"
+DEPENDS = "python3 flex-native bison-native"
 
 PACKAGES += "python3-sip3"
 
@@ -25,6 +25,11 @@ CONFIGURE_SYSROOT = "${STAGING_DIR_HOST}"
 CONFIGURE_SYSROOT:class-native = "${STAGING_DIR_NATIVE}"
 
 do_configure:prepend() {
+    # Re-generate the lexical analyzer and parser
+    # Required for the py_ssize_t_clean patch
+    flex --outfile=sipgen/lexer.c sipgen/metasrc/lexer.l
+    bison --yacc -Wcounterexamples --defines=sipgen/parser.h --output=sipgen/parser.c sipgen/metasrc/parser.y
+
     echo "py_platform = linux" > sip.cfg
     echo "py_inc_dir = ${STAGING_INCDIR}/python%(py_major).%(py_minor)${PYTHON_ABI}" >> sip.cfg
     echo "sip_bin_dir = ${D}/${bindir}" >> sip.cfg