Build Fails on Musl LibC

[oneechanhax]

It appears to conflict with defines from the libc.

/ocvm.reproduce$ make lua=lua5.3 CXX=clang 
clang  -I/usr/include/lua5.3 -MMD -MP -Wall -g --std=c++17 -O0 -Wl,--no-as-needed -I. -Iapis -Icolor -Icomponents -Idrivers -Iio -Imodel -Iutil -c drivers/internet_http.cpp -o bin/drivers/internet_http.cpp.o
clang: warning: -Wl,--no-as-needed: 'linker' input unused [-Wunused-command-line-argument]
drivers/internet_http.cpp:129:27: error: expected unqualified-id
  129 | Connection* PipedCommand::stdin() const
      |                           ^
drivers/internet_http.cpp:134:27: error: expected unqualified-id
  134 | Connection* PipedCommand::stdout() const
      |                           ^
drivers/internet_http.cpp:139:27: error: expected unqualified-id
  139 | Connection* PipedCommand::stderr() const
      |                           ^
drivers/internet_http.cpp:197:29: error: expected unqualified-id
  197 |     Connection* resp = _cmd.stderr();
      |                             ^
/usr/include/stdio.h:68:16: note: expanded from macro 'stderr'
   68 | #define stderr (stderr)
      |                ^
drivers/internet_http.cpp:282:15: error: expected unqualified-id
  282 |   return _cmd.stdout();
      |               ^
/usr/include/stdio.h:67:16: note: expanded from macro 'stdout'
   67 | #define stdout (stdout)
      |                ^
5 errors generated.
make: *** [Makefile:46: bin/drivers/internet_http.cpp.o] Error 1

Easy dumb way to fix it and make it compile for me.

#undef stdin

Connection* PipedCommand::stdin() const
{
  return _stdin.get();
}

#undef stdout
Connection* PipedCommand::stdout() const
{
  return _stdout.get();
}

#undef stderr
Connection* PipedCommand::stderr() const
{
  return _stderr.get();
}

A better way to do this is to do it conditionally.
If the system is linux, but not GNU libc.

Unsure about the other variants of libc and if they define these the same way.