/usr/bin/ld: cannot find -lboost_system-mgw46-mt-sd-1_53
/usr/bin/ld: cannot find -lboost_filesystem-mgw46-mt-sd-1_53
/usr/bin/ld: cannot find -lboost_program_options-mgw46-mt-sd-1_53
/usr/bin/ld: cannot find -lboost_thread-mgw46-mt-sd-1_53
collect2: error: ld returned 1 exit status
make: *** [Sexcoin-qt] Error 1
You have to clean the Makefile file after doing qmake. It has been built using windows project.
I've copied LIBS from another coin Makefile, and removed references to C: