clang -O2  -Wall -Wextra -Werror=implicit-function-declaration signal/sigaltstack.c -o signal/sigaltstack -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE  -lm  -lintl
../out/minix/basic/signal/sigaltstack.o: In function `main':
signal/sigaltstack.c:(.text+0x33c): undefined reference to `__sigaltstack14'
../out/minix/basic/signal/sigaltstack.o: In function `handler':
signal/sigaltstack.c:(.text+0x511): undefined reference to `__sigaltstack14'
clang: error: linker command failed with exit code 1 (use -v to see invocation)