science/svmlight: fix build on 13.0+

cc -O2 -pipe -fPIC -fstack-protector-strong -fno-strict-aliasing svm_learn_main.o svm_learn.o svm_common.o svm_hideo.o -o svm_learn -L. -lm
ld: error: duplicate symbol: verbosity

defined at svm_common.c

svm_common.o:(verbosity)

defined at svm_hideo.c

svm_hideo.o:(.bss+0x38)

cc: error: linker command failed with exit code 1 (use -v to see invocation)