The stdio stream identifiers (stdin, stdout, stderr) are allowed to be macros.
In musl libc they are, for example doing `#define stdout (stdout)`, breaking
compilation with an error when one of the clashing variables is attempted to be
initialized the "wrong" way:
../lix/libutil/processes.cc:272:7: error: expected class member or base class name
272 | , stdout(stdout ? std::make_unique<AsyncFdIoStream>(std::move(stdout)) : nullptr)
| ^
/nix/store/ziw42d7rvgnf3vkbfc8kry07kipwf1xm-musl-static-x86_64-unknown-linux-musl-1.2.5-dev/include/stdio.h:67:16: note: expanded from macro 'stdout'
67 | #define stdout (stdout)
| ^
Other places only cause warnings on musl:
../lix/libutil/processes.cc:254:17: warning: parentheses were disambiguated as redundant parentheses around declaration of variable named 'stdout' [-Wvexing-parse]
254 | std::string stdout;
| ^~~~~~
/nix/store/ziw42d7rvgnf3vkbfc8kry07kipwf1xm-musl-static-x86_64-unknown-linux-musl-1.2.5-dev/include/stdio.h:67:16: note: expanded from macro 'stdout'
67 | #define stdout (stdout)
| ^~~~~~~~
../lix/libutil/processes.cc:254:17: note: add a variable name to declare a 'std::string' (aka 'basic_string<char>') initialized with 'stdout'
254 | std::string stdout;
| ^
| varname
/nix/store/ziw42d7rvgnf3vkbfc8kry07kipwf1xm-musl-static-x86_64-unknown-linux-musl-1.2.5-dev/include/stdio.h:67:16: note: expanded from macro 'stdout'
67 | #define stdout (stdout)
| ^
../lix/libutil/processes.cc:254:5: note: add enclosing parentheses to perform a function-style cast
254 | std::string stdout;
| ^
| ( )
../lix/libutil/processes.cc:254:17: note: remove parentheses to silence this warning
254 | std::string stdout;
| ^
/nix/store/ziw42d7rvgnf3vkbfc8kry07kipwf1xm-musl-static-x86_64-unknown-linux-musl-1.2.5-dev/include/stdio.h:67:16: note: expanded from macro 'stdout'
67 | #define stdout (stdout)
| ^
However they are still wrong, since the macro could be more complicated. Fix
them as well.
Change-Id: I6a6a6964a50ef7dec8f05f0bd8fc8f13f3036d51