tools/python: Pass linker to Python build process

Unexpectedly the environment variable which needs to be passed is
$LDSHARED and not $LD.  Otherwise Python may find the build `ld` instead
of the host `ld`.

Replace $(LDFLAGS) with $(SHLIB_LDFLAGS) as Python needs shared objects
it can load at runtime, not executables.

This uses $(CC) instead of $(LD) since Python distutils appends $CFLAGS
to $LDFLAGS which breaks many linkers.

Signed-off-by: Elliott Mitchell <ehem+xen@m5p.com>
Acked-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>

tools/python/Makefile

@@ -5,19 +5,20 @@ include $(XEN_ROOT)/tools/Rules.mk
 all: build
 
 PY_CFLAGS = $(CFLAGS) $(PY_NOOPT_CFLAGS)
-PY_LDFLAGS = $(LDFLAGS) $(APPEND_LDFLAGS)
+PY_LDFLAGS = $(SHLIB_LDFLAGS) $(APPEND_LDFLAGS)
 INSTALL_LOG = build/installed_files.txt
 
 .PHONY: build
 build:
-	CC="$(CC)" CFLAGS="$(PY_CFLAGS)" $(PYTHON) setup.py build
+	CC="$(CC)" CFLAGS="$(PY_CFLAGS)" LDSHARED="$(CC)" LDFLAGS="$(PY_LDFLAGS)" $(PYTHON) setup.py build
 
 .PHONY: install
 install:
 	$(INSTALL_DIR) $(DESTDIR)$(LIBEXEC_BIN)
 
-	CC="$(CC)" CFLAGS="$(PY_CFLAGS)" LDFLAGS="$(PY_LDFLAGS)" $(PYTHON) \
-		setup.py install --record $(INSTALL_LOG) $(PYTHON_PREFIX_ARG) \
+	CC="$(CC)" CFLAGS="$(PY_CFLAGS)" LDSHARED="$(CC)" \
+		LDFLAGS="$(PY_LDFLAGS)" $(PYTHON) setup.py install \
+		--record $(INSTALL_LOG) $(PYTHON_PREFIX_ARG) \
 		--root="$(DESTDIR)" --force
 
 	$(INSTALL_PYTHON_PROG) scripts/convert-legacy-stream $(DESTDIR)$(LIBEXEC_BIN)