Support building for a gcc other than the host compiler

This allows compiling a gcc-python-plugin to run in the context of a
cross-compiler.  Using the cross-compiler to build gcc-python-plugin
would produce a plugin that cannot be loaded on the host system.

Author: Kevin Pyle

Makefile

@@ -55,10 +55,12 @@ PLUGIN_GENERATED_SOURCE_FILES:= \
   autogenerated-tree.c \
   autogenerated-variable.c
 
+TARGET_GCC:=$(CC)
+
 PLUGIN_OBJECT_SOURCE_FILES:= $(patsubst %.c,%.o,$(PLUGIN_SOURCE_FILES))
 PLUGIN_OBJECT_GENERATED_FILES:= $(patsubst %.c,%.o,$(PLUGIN_GENERATED_SOURCE_FILES))
 PLUGIN_OBJECT_FILES:= $(PLUGIN_OBJECT_SOURCE_FILES) $(PLUGIN_OBJECT_GENERATED_FILES)
-GCCPLUGINS_DIR:= $(shell $(CC) --print-file-name=plugin)
+GCCPLUGINS_DIR:= $(shell $(TARGET_GCC) --print-file-name=plugin)
 
 GENERATOR_DEPS=cpybuilder.py wrapperbuilder.py print-gcc-version
 
@@ -132,7 +134,7 @@ plugin: autogenerated-config.h $(PLUGIN_DSO)
 # When running the plugin from a working copy, use LD_LIBARY_PATH=gcc-c-api
 # so that the plugin can find its libgcc-c-api.so there
 #
-INVOCATION_ENV_VARS := LD_LIBRARY_PATH=gcc-c-api CC=$(CC)
+INVOCATION_ENV_VARS := LD_LIBRARY_PATH=gcc-c-api CC="$(TARGET_GCC)"
 
 # When installing, both the plugin and libgcc-c-api.so will be installed to
 # $(GCCPLUGINS_DIR), so we give the plugin an RPATH of $(GCCPLUGINS_DIR)
@@ -149,7 +151,7 @@ $(PLUGIN_DSO): $(PLUGIN_OBJECT_FILES) $(LIBGCC_C_API_SO)
 	    -lgcc-c-api -Lgcc-c-api -Wl,-rpath=$(GCCPLUGINS_DIR)
 
 $(LIBGCC_C_API_SO):
-	cd gcc-c-api && make libgcc-c-api.so CC=$(CC)
+	cd gcc-c-api && make libgcc-c-api.so CC="$(CC)" TARGET_GCC="$(TARGET_GCC)"
 
 $(PLUGIN_OBJECT_GENERATED_FILES): CPPFLAGS+= $(if $(srcdir),-I$(srcdir))
 
@@ -170,11 +172,11 @@ clean:
 	$(RM) -r docs/_build
 	$(RM) -f gcc-with-$(PLUGIN_NAME).1 gcc-with-$(PLUGIN_NAME).1.gz
 	$(RM) -f print-gcc-version
-	cd gcc-c-api && make clean
+	cd gcc-c-api && make clean CC="$(CC)" TARGET_GCC="$(TARGET_GCC)"
 	find tests -name "*.o" -delete
 
 autogenerated-config.h: $(addprefix $(srcdir),generate-config-h.py configbuilder.py)
-	$(PYTHON) $< -o $@ --gcc="$(CC)" --plugindir="$(GCCPLUGINS_DIR)"
+	$(PYTHON) $< -o $@ --gcc="$(TARGET_GCC)" --plugindir="$(GCCPLUGINS_DIR)"
 
 autogenerated-%.txt: $(srcdir)%.txt.in
 	$(CPP) $(CPPFLAGS) -x c-header $^ -o $@
@@ -266,7 +268,7 @@ TEST_CFLAGS= \
 
 # A catch-all test for quick experimentation with the API:
 test: plugin
-	$(INVOCATION_ENV_VARS) $(CC) -v $(TEST_CFLAGS) $(CURDIR)/test.c
+	$(INVOCATION_ENV_VARS) $(TARGET_GCC) -v $(TEST_CFLAGS) $(CURDIR)/test.c
 
 # Selftest for the cpychecker.py code:
 testcpychecker: plugin
@@ -277,10 +279,10 @@ testcpybuilder:
 	$(PYTHON) testcpybuilder.py -v
 
 dump_gimple:
-	$(CC) -fdump-tree-gimple $(CURDIR)/test.c
+	$(TARGET_GCC) -fdump-tree-gimple $(CURDIR)/test.c
 
 debug: plugin
-	$(INVOCATION_ENV_VARS) $(CC) -v $(TEST_CFLAGS) $(CURDIR)/test.c
+	$(INVOCATION_ENV_VARS) $(TARGET_GCC) -v $(TEST_CFLAGS) $(CURDIR)/test.c
 
 # A simple demo, to make it easy to demonstrate the cpychecker:
 demo: plugin

gcc-c-api/Makefile

@@ -70,7 +70,9 @@ GENERATED_HEADERS:= \
   gcc-type.h \
   gcc-variable.h
 
-GCCPLUGINS_DIR:= $(shell $(CC) --print-file-name=plugin)
+TARGET_GCC:=$(CC)
+
+GCCPLUGINS_DIR:= $(shell $(TARGET_GCC) --print-file-name=plugin)
 
 LIBGCC_C_API_SO	:= libgcc-c-api.so