Add missing thrust include

[puzzlepaint]

Adding this include was necessary to compile popsift in my environment (with CUDA release 11.4, V11.4.48).

[simogasp]

LGTM!
Thanks for your contribution!

[simogasp]

Just for reference, here is the log to the compilation error with cuda 11.4

popsift/src/popsift/s_filtergrid.cu(204): error: namespace "thrust" has no member "host_vector"

popsift/src/popsift/s_filtergrid.cu(204): error: type name is not allowed

popsift/src/popsift/s_filtergrid.cu(204): error: identifier "h_cell_counts" is undefined

popsift/src/popsift/s_filtergrid.cu(205): error: namespace "thrust" has no member "host_vector"

popsift/src/popsift/s_filtergrid.cu(205): error: type name is not allowed

popsift/src/popsift/s_filtergrid.cu(205): error: identifier "h_cell_permute" is undefined

popsift/src/popsift/s_filtergrid.cu(206): error: namespace "thrust" has no member "host_vector"

popsift/src/popsift/s_filtergrid.cu(206): error: type name is not allowed

popsift/src/popsift/s_filtergrid.cu(206): error: identifier "h_cell_offsets" is undefined

popsift/src/popsift/s_filtergrid.cu(207): error: namespace "thrust" has no member "host_vector"

popsift/src/popsift/s_filtergrid.cu(207): error: type name is not allowed

popsift/src/popsift/s_filtergrid.cu(207): error: identifier "h_cell_limits" is undefined

popsift/src/popsift/s_filtergrid.cu(208): error: namespace "thrust" has no member "host_vector"

popsift/src/popsift/s_filtergrid.cu(208): error: type name is not allowed

popsift/src/popsift/s_filtergrid.cu(208): error: identifier "cell_count_prefix_sums" is undefined

popsift/src/popsift/s_filtergrid.cu(209): error: namespace "thrust" has no member "host_vector"

popsift/src/popsift/s_filtergrid.cu(209): error: type name is not allowed

popsift/src/popsift/s_filtergrid.cu(209): error: identifier "cell_count_sumup" is undefined

popsift/src/popsift/s_filtergrid.cu(230): error: namespace "thrust" has no member "host_vector"

popsift/src/popsift/s_filtergrid.cu(230): error: type name is not allowed

popsift/src/popsift/s_filtergrid.cu(230): error: identifier "h_reverse_index" is undefined

21 errors detected in the compilation of "popsift/src/popsift/s_filtergrid.cu".
CMake Error at popsift_generated_s_filtergrid.cu.o.Release.cmake:280 (message):
  Error generating file
  external/popsift_build/src/CMakeFiles/popsift.dir/popsift/./popsift_generated_s_filtergrid.cu.o