compatibility for android with ndk toolchain

[eventlOwOp]

problem

when cross compiling zerotier using ndk toolchain (for android)

it satisfied #if defined(__LINUX__) && ( (!defined(__GLIBC__)) || ((__GLIBC__ >= 2) && (__GLIBC_MINOR__ >= 18)) ) on line 2097 and called pthread_setattr_default_np which is not supported in ndk

one.cpp:2097:2: error: use of undeclared identifier 'pthread_setattr_default_np'
        pthread_setattr_default_np(&tattr);
        ^
1 warning and 1 error generated.
make: *** [<builtin>: one.o] Error 1
make: *** Waiting for unfinished jobs....

to reproduce

make ZT_STATIC=1 ZT_DEBUG=0 ZT_SSO_SUPPORTED=0 CC=aarch64-linux-android33-clang CXX=aarch64-linux-android33-clang++ LDFLAGS="-s -L../deps/aarch64" DEFS="-I../deps/include" ( in ubuntu with ndk toolchain, LDFLAGS and DEFS are set to link the natpmpc library built myself )
or
make ZT_STATIC=1 ZT_DEBUG=0 ZT_SSO_SUPPORTED=0 ( in termux after installing natpmpc apt-get install -y natpmpc )

possible solution

change that line into

#if defined(__LINUX__) && ( (!defined(__GLIBC__)) || ((__GLIBC__ >= 2) && (__GLIBC_MINOR__ >= 18)) ) && (!defined(__ANDROID__))