Add align feature to pthread structs

src/fuchsia/mod.rs

src/macros.rs

src/unix/newlib/mod.rs

src/unix/notbsd/emscripten.rs

src/unix/notbsd/linux/mips/mips32.rs

src/unix/notbsd/linux/mips/mips64.rs

src/unix/notbsd/linux/mod.rs

src/unix/notbsd/linux/other/b32/mod.rs

src/unix/notbsd/linux/other/b64/aarch64.rs

src/unix/notbsd/linux/other/b64/not_x32.rs

src/unix/notbsd/linux/other/b64/powerpc64.rs

src/unix/notbsd/linux/other/b64/sparc64.rs

src/unix/notbsd/linux/other/b64/x32.rs

src/unix/notbsd/linux/s390x.rs

src/unix/uclibc/mod.rs

src/unix/uclibc/x86_64/mod.rs