Pedantic compiler warnings

[jeroen]

Would be nice to have an easy way to enable -pedantic warnings in CMD check. I think this is most easily implemented by writing some flags to ~/.R/Makevars.

CFLAGS += -O3 -Wall -pipe -pedantic -std=gnu99
CXXFLAGS += -O3 -Wall -pipe -Wno-unused -pedantic 
FFLAGS += -O3 -g0 -Wall -pipe
FCFLAGS += -O3 -g0 -Wall -pipe
CXX1XFLAGS=-O3 -Wall -pipe -Wno-unused -pedantic