sudo bash   # (escalate to root user)
cd   # switch to root's home directory, which is where I cloned it originally.
cd verilator
make uninstall
cd ..
rm -rf verilator
unset VERILATOR_ROOT
git clone http://git.veripool.org/git/verilator
git checkout stable
autoconf
./configure --prefix=/opt/verilator
make
make test && make install
exit  # back to normal privilege account.

mkdir project
cd project
cat <<EOF >dmac.v
module dmac;
         initial begin $display("Hello World"); $finish; end
endmodule
EOF
cat <<EOF >dmac.cpp
#include "Vour.h"
#include "verilated.h"
int main(int argc, char **argv, char **env) {
         Verilated::commandArgs(argc, argv);
         Vdmac *top = new Vdmac;
         while (!Verilated::gotFinish()) { top->eval(); }
         delete top;
         exit(0);
}
EOF
unset VERILATOR_ROOT    #<-- this is what made everything work, I believe
verilator -Wall --cc dmac.v --exe dmac.cpp
make -j -C obj_dir -f Vdmac.mk Vdmac
obj_dir/Vdmac

mkdir -p bench/cpp rtl/verilog
mv dmac.v rtl/verilog
mv dmac.cpp bench/cpp
rm -rf obj_dir
verilator -Wall --cc rtl/verilog/dmac.v --exe bench/cpp/dmac.cpp
make -j -C obj_dir -f Vdmac.mk Vdmac
obj_dir/Vdmac

I hope this helps others who run into the same problems I have.