can't find file sparsehash/internal/sparseconfig.h about sparsehash HOT 2 CLOSED

my@pc:~/sparsehash$ find . -name sparseconfig.h
./src/windows/google/sparsehash/sparseconfig.h
./src/windows/sparsehash/internal/sparseconfig.h
my@pc:~/sparsehash$ ./configure --prefix=$PWD > /dev/null
my@pc:~/sparsehash$ find . -name sparseconfig.h
./src/windows/google/sparsehash/sparseconfig.h
./src/windows/sparsehash/internal/sparseconfig.h
my@pc:~/sparsehash$ make -j > /dev/null
my@pc:~/sparsehash$ find . -name sparseconfig.h
./src/sparsehash/internal/sparseconfig.h
./src/windows/google/sparsehash/sparseconfig.h
./src/windows/sparsehash/internal/sparseconfig.h