Issue #27490: Do not build pgen when cross-compiling

The dependendency on the $(PGEN) variable must only be
set when not cross-compiling. When cross-compiling,
$(PGEN) will not be used, so no need to build it.

Patch by Thomas Perl.

configure

@@ -739,6 +739,7 @@ UNIVERSALSDK
 CONFIG_ARGS
 SOVERSION
 VERSION
+PGEN_DEPENDENCY
 PYTHON_FOR_BUILD
 PYTHON_FOR_GEN
 host_os
@@ -3049,14 +3050,17 @@ $as_echo_n "checking for python interpreter for cross build... " >&6; }
 $as_echo "$interp" >&6; }
 	PYTHON_FOR_BUILD='_PYTHON_PROJECT_BASE=$(abs_builddir) _PYTHON_HOST_PLATFORM=$(_PYTHON_HOST_PLATFORM) PYTHONPATH=$(shell test -f pybuilddir.txt && echo $(abs_builddir)/`cat pybuilddir.txt`:)$(srcdir)/Lib:$(srcdir)/Lib/$(PLATDIR) '$interp
     fi
+    PGEN_DEPENDENCY=''
 elif test "$cross_compiling" = maybe; then
     as_fn_error $? "Cross compiling required --host=HOST-TUPLE and --build=ARCH" "$LINENO" 5
 else
     PYTHON_FOR_BUILD='./$(BUILDPYTHON) -E'
+    PGEN_DEPENDENCY='$(PGEN)'
 fi
 
 
 
+
 if test "$prefix" != "/"; then
     prefix=`echo "$prefix" | sed -e 's/\/$//g'`
 fi