[Rd] Alternative for wildcard gnu extension in Makevars

[Jan van der Laan]

I have some cpp-files from another library (boost) in a subdirectory  
in my src directory (src/boost_src). I include these using the  
following two lines in my Makevars:

SOURCES = $(wildcard *.cpp boost_src/*.cpp)
OBJECTS = $(SOURCES:.cpp=.o)

However, R CMD check complains about my use of 'wildcard'. How do I  
handle this without any gnu extensions?

Thanks.
Jan