Build static library of gRPC

If you want to build static library of gRPC, you can check following steps:

$ git clone https://github.com/grpc/grpc.git
$ cd grpc
$ git submodule update --init
$ CC=clang CXX=clang++ make REQUIRE_CUSTOM_LIBRARIES_opt=1 static

If you bump into following errors:

third_party/protobuf/src/google/protobuf/stubs/port.h:263:5: error: macro expansion producing 'defined' has undefined
  behavior [-Werror,-Wexpansion-to-defined]
#if GOOGLE_PROTOBUF_USE_UNALIGNED
    ^

Please check this patch. After compile, you can find all libraries are static:

$ ls -alt libs/opt/*
-rw-r--r-- 1 xiaonan xiaonan  8109188 Oct  6 17:54 libs/opt/libgrpc++_unsecure.a
-rw-r--r-- 1 xiaonan xiaonan  3705192 Oct  6 17:54 libs/opt/libgrpc++_reflection.a
-rw-r--r-- 1 xiaonan xiaonan  2089436 Oct  6 17:54 libs/opt/libgrpc++_error_details.a
-rw-r--r-- 1 xiaonan xiaonan 24675866 Oct  6 17:54 libs/opt/libgrpc++_cronet.a
-rw-r--r-- 1 xiaonan xiaonan  9276572 Oct  6 17:54 libs/opt/libgrpc++.a
-rw-r--r-- 1 xiaonan xiaonan   917148 Oct  6 17:54 libs/opt/libgrpc++_core_stats.a
-rw-r--r-- 1 xiaonan xiaonan  7180018 Oct  6 17:54 libs/opt/libgrpc_plugin_support.a
-rw-r--r-- 1 xiaonan xiaonan  8163444 Oct  6 17:41 libs/opt/libgrpc_unsecure.a
-rw-r--r-- 1 xiaonan xiaonan 18854796 Oct  6 17:41 libs/opt/libgrpc_cronet.a
-rw-r--r-- 1 xiaonan xiaonan 20064046 Oct  6 17:41 libs/opt/libgrpc.a
-rw-r--r-- 1 xiaonan xiaonan 10669618 Oct  6 17:40 libs/opt/libboringssl.a
-rw-r--r-- 1 xiaonan xiaonan   456458 Oct  6 17:39 libs/opt/libgpr.a
-rw-r--r-- 1 xiaonan xiaonan   379730 Oct  6 17:39 libs/opt/libz.a
-rw-r--r-- 1 xiaonan xiaonan   629666 Oct  6 17:39 libs/opt/libares.a

libs/opt/protobuf:
total 114748
drwxr-xr-x 4 xiaonan xiaonan     4096 Oct  6 17:54 ..
-rw-r--r-- 1 xiaonan xiaonan 50492478 Oct  6 17:49 libprotobuf.a
drwxr-xr-x 2 xiaonan xiaonan     4096 Oct  6 17:49 .
-rw-r--r-- 1 xiaonan xiaonan 66986782 Oct  6 17:49 libprotoc.a

libs/opt/pkgconfig:
total 24
drwxr-xr-x 4 xiaonan xiaonan 4096 Oct  6 17:54 ..
drwxr-xr-x 2 xiaonan xiaonan 4096 Oct  6 17:41 .
-rw-r--r-- 1 xiaonan xiaonan  283 Oct  6 17:41 grpc++_unsecure.pc
-rw-r--r-- 1 xiaonan xiaonan  253 Oct  6 17:41 grpc++.pc
-rw-r--r-- 1 xiaonan xiaonan  283 Oct  6 17:39 grpc_unsecure.pc
-rw-r--r-- 1 xiaonan xiaonan  264 Oct  6 17:39 grpc.pc