Usage of _unused macro conflicts with linux-headers on PowerPC

[matoro]

I am unsure what specific change (or kernel headers change) caused this, but I am unable to compile the new release on PowerPC (both BE/LE tested 64-bit) due to the following error:

FAILED: src/librc/librc.so.1.p/librc.c.o 
powerpc64le-unknown-linux-gnu-gcc -Isrc/librc/librc.so.1.p -Isrc/librc -I../openrc-0.47/src/librc -Isrc/shared -I../openrc-0.47/src/shared -Isrc/libeinfo -I../openrc-0.47/src/libeinfo -fdiagnostics-color=always -D_FILE_OFFSET_BITS=64 -Wall -Winvalid-pch -Wextra -Wpedantic -std=c99 -D_DEFAULT_SOURCE -Wcast-align -Wcast-qual -Wdeclaration-after-statement -Wformat=2 -Winline -Wmissing-declarations -Wmissing-format-attribute -Wmissing-noreturn -Wmissing-prototypes -Wnested-externs -Wpointer-arith -Wsequence-point -Wshadow -Wwrite-strings -Werror=implicit-function-declaration -DHAVE_MALLOC_EXTENDED_ATTRIBUTE -DHAVE_CLOSEFROM -DHAVE_CLOSE_RANGE_CLOEXEC -O3 -mcpu=native -mtune=native -O2 -pipe -fPIC -MD -MQ src/librc/librc.so.1.p/librc.c.o -MF src/librc/librc.so.1.p/librc.c.o.d -o src/librc/librc.so.1.p/librc.c.o -c ../openrc-0.47/src/librc/librc.c
In file included from /usr/include/bits/sigcontext.h:30,
                 from /usr/include/signal.h:301,
                 from /usr/include/sys/param.h:28,
                 from ../openrc-0.47/src/librc/librc.c:30:
/usr/include/asm/sigcontext.h:18:32: error: expected identifier or ‘(’ before ‘[’ token
   18 |         unsigned long   _unused[4];
      |                                ^
ninja: build stopped: subcommand failed.

[thesamesam]

I'll handle this later today/tomorrow. It's because we started using the (already-existing) unused macros in different locations, but __foo is always reserved, and it happens to conflict with some padding on ppc64 (but it could be anything else on other systems).

[vapier]

both projects are wrong. we can fix ours at least. go with attr_xxx instead of _xxx or something. and drop support for <gcc-3 in the process.