Add a Cppcheck makefile for parallel building

The one-shot command works, but only use a single core. This build
benefits significantly from parallelization, and make is the easiest way
to do it. Since the original Cppcheck makefile doesn't do the right
thing, supply a custom build.

Dockerfile

@@ -421,11 +421,8 @@ RUN sed -i /RT_MANIFEST/d win32/ctags.rc \
  && cp ctags.exe $PREFIX/bin/
 
 WORKDIR /cppcheck-$CPPCHECK_VERSION
-RUN $ARCH-g++ -Os -s -o cppcheck.exe \
- -Ilib -Iexternals/simplecpp -Iexternals/tinyxml2 -Iexternals/picojson \
- cli/*.cpp lib/*.cpp \
- externals/tinyxml2/tinyxml2.cpp externals/simplecpp/simplecpp.cpp \
- -lshlwapi \
+COPY src/cppcheck.mak $PREFIX/src/
+RUN make -f $PREFIX/src/cppcheck.mak -j$(nproc) CXX=$ARCH-g++ \
  && mkdir $PREFIX/share/cppcheck/ \
  && cp -r cppcheck.exe cfg/ $PREFIX/share/cppcheck \
  && $ARCH-gcc -DEXE=../share/cppcheck/cppcheck.exe -DCMD=cppcheck \

src/cppcheck.mak

@@ -0,0 +1,8 @@
+ext := $(shell find externals -mindepth 1 -type d)
+src := $(shell find cli lib externals -name '*.cpp')
+obj := $(src:.cpp=.o)
+CXXFLAGS := -Os -Ilib $(addprefix -I,$(ext))
+LDFLAGS := -s
+LDLIBS := -lshlwapi
+cppcheck$(EXE): $(obj)
+ $(CXX) $(LDFLAGS) -o $@ $(obj) $(LDLIBS)