Speed up compiling process

[emailweixu]

Currently, the compile takes too long (20+ min on my machine for some changes in paddle/platform). We should make it faster. Even if we only save 1 minute for the compilation, it translates to a save hundreds of minutes each day because each developer will compile tens of times and can speed up our development speed considerably.

So this is very high value issue.

[emailweixu]

Trying to see if ccache can work with nvcc.

[qingqing01]

It seems the ccache does not work for nvcc. Add the ccache for nvcc as follows, the time is same when compiling twice.

time /home/dangqingqing/.jumbo/bin/ccache /usr/local/cuda/bin/nvcc /home/dangqingqing/github/myfork/Paddle/paddle/operators/elementwise_mul_op.cu -c -o /home/dangqingqing/github/myfork/build/paddle/operators/CMakeFiles/elementwise_mul_op.dir//./elementwise_mul_op_generated_elementwise_mul_op.cu.o -ccbin /home/dangqingqing/.jumbo/opt/gcc48/bin/g++ -m64 -DANY_IMPL_ANY_CAST_MOVEABLE -DPADDLE_USE_DSO -DPADDLE_WITH_TESTING -DPADDLE_DISABLE_TIMER -DPADDLE_DISABLE_PROFILER -DPADDLE_WITHOUT_GOLANG -DPADDLE_WITH_CUDA -DPADDLE_DISABLE_RDMA -DPADDLE_USE_PTHREAD_SPINLOCK -DPADDLE_USE_PTHREAD_BARRIER -DPADDLE_VERSION=0.10.0rc4 -gencode arch=compute_30,code=sm_30 -gencode arch=compute_35,code=sm_35 -gencode arch=compute_50,code=sm_50 -gencode arch=compute_52,code=sm_52 -Xcompiler -mavx -Xcompiler -Wall -Xcompiler -Wextra -Xcompiler -Werror -Xcompiler -fPIC -Xcompiler -fno-omit-frame-pointer -Xcompiler -Wno-unused-parameter -Xcompiler -Wno-unused-function -Xcompiler -Wno-error=sign-compare -Xcompiler -Wno-error=literal-suffix -Xcompiler -Wno-error=unused-local-typedefs -Xcompiler -Wno-error=unused-function -Xcompiler -Wno-error=array-bounds -std=c++11 --use_fast_math -O2 -g -DNDEBUG -DNVCC -I/usr/local/cuda/include -I/home/dangqingqing/.third_party/install/zlib/include -I/home/dangqingqing/.third_party/install/gflags/include -I/home/dangqingqing/.third_party/install/glog/include -I/home/dangqingqing/.third_party/install/gtest/include -I/home/dangqingqing/.third_party/install/protobuf/include -I/home/dangqingqing/.jumbo/include/python2.7 -I/home/dangqingqing/.jumbo/lib/python2.7/site-packages/numpy/core/include -I/home/dangqingqing/.third_party/install/openblas/include -I/home/dangqingqing/.third_party/install/warpctc/include -I/home/dangqingqing/.third_party/any/src/extern_lib_any -I/home/dangqingqing/.third_party/eigen3/src/extern_eigen3 -I/home/dangqingqing/.third_party/pybind/src/extern_pybind/include -I/home/dangqingqing/.third_party/nccl/src/extern_nccl/src -I/usr/local/cuda/include -I/home/dangqingqing/github/myfork/build -I/home/dangqingqing/github/myfork/Paddle -I/home/dangqingqing/github/myfork/Paddle/paddle/cuda/include -I/home/dangqingqing/github/myfork/build/proto -I/home/dangqingqing/github/myfork/build/go/pserver/client/c -I/usr/include