luffa/cube: fine tuning of maxregcount for the 750Ti

This allow to get 69 regs used (tested on linux) 69 or 72 make
the compiler to use 64 regs which is not enough on the 750Ti
for optimal performance...

Makefile.am

@@ -105,7 +105,7 @@ x11/cuda_x11_luffa512.o: x11/cuda_x11_luffa512.cu
 	$(NVCC) $(nvcc_FLAGS) --maxrregcount=80 -o $@ -c $<
 
 x11/cuda_x11_luffa512_Cubehash.o: x11/cuda_x11_luffa512_Cubehash.cu
-	$(NVCC) $(nvcc_FLAGS) --maxrregcount=80 -o $@ -c $<
+	$(NVCC) $(nvcc_FLAGS) --maxrregcount=76 -o $@ -c $<
 
 x13/cuda_x13_hamsi512.o: x13/cuda_x13_hamsi512.cu
 	$(NVCC) $(nvcc_FLAGS) --maxrregcount=72 -o $@ -c $<

ccminer.vcxproj

@@ -455,7 +455,7 @@
     </CudaCompile>
     <CudaCompile Include="x11\cuda_x11_luffa512.cu" />
     <CudaCompile Include="x11\cuda_x11_luffa512_Cubehash.cu">
-      <MaxRegCount>80</MaxRegCount>
+      <MaxRegCount>76</MaxRegCount>
     </CudaCompile>
     <CudaCompile Include="x11\cuda_x11_shavite512.cu">
       <MaxRegCount>128</MaxRegCount>

x11/cuda_x11_luffa512_Cubehash.cu

@@ -731,8 +731,6 @@ static void finalization512(uint32_t *statebuffer, uint32_t *statechainv, uint32
 __global__
 #if __CUDA_ARCH__ > 500
 __launch_bounds__(256, 4)
-#else
-__launch_bounds__(256, 3)
 #endif
 void x11_luffaCubehash512_gpu_hash_64(uint32_t threads, uint32_t *g_hash)
 {