unix: remove always_inline attribute

Fixes the following gcc 4.7+ warning:

  ../src/unix/internal.h:105:13: warning: always_inline function might not be
  inlinable [-Wattributes]

gcc wants the always_inline function to be annotated with the 'inline' keyword
which we can't do because we compile in C89 mode.

Using __inline is not an option because that makes clang generate warnings when
-Wlanguage-extension-token is enabled.

Therefore, remove the always_inline attribute altogether and hope that the
compiler is smart enough to inline the functions.

src/unix/async.c

@@ -30,7 +30,6 @@ static int uv__async_init(uv_loop_t* loop);
 static void uv__async_io(uv_loop_t* loop, uv__io_t* handle, int events);
 
 
-__attribute__((always_inline))
 static int uv__async_make_pending(volatile sig_atomic_t* ptr) {
   /* Do a cheap read first. */
   if (*ptr)

src/unix/internal.h

@@ -101,7 +101,6 @@ enum {
 };
 
 __attribute__((unused))
-__attribute__((always_inline))
 static void uv__req_init(uv_loop_t* loop, uv_req_t* req, uv_req_type type) {
   req->type = type;
   uv__req_register(loop, req);