Build on OSX with clang 11 reports warnings

[vkuzmin-uber]

Two warnings during build on OSX with clang

g++ --version
Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/c++/4.2.1
Apple clang version 11.0.0 (clang-1100.0.33.12)
Target: x86_64-apple-darwin18.7.0
Thread model: posix
InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin

1st:

INFO: From Compiling neuropods/multiprocess/multiprocess.cc:
neuropods/multiprocess/multiprocess.cc:37:9: warning: ISO C++11 does not allow conversion from string literal to 'char *' [-Wwritable-strings]
        "neuropod_multiprocess_worker",

here explicit cast helps

2nd:

INFO: From Compiling neuropods/multiprocess/ipc_control_channel.cc:
In file included from neuropods/multiprocess/ipc_control_channel.cc:10:
./neuropods/multiprocess/shm_tensor.hh:39:7: warning: unused function 'get_next_aligned_offset' [-Wunused-function]
void *get_next_aligned_offset(void *base)

Compiler warning is not correct, function is used. Function is defined in header and making it "inline" fixes warning and is reasonable at the same time.

I can provide pull request