Revert "[macos] Fix warnings around syscall deprecation on OS X 10.12 and up"

This reverts commit a8a17dab303dd83a857b1f3d557ca323cd8fbce8.

This is incorrect and breaks on Linux.

Change-Id: I0afb511a540cb737e8267597c1ccf1d024f52261
diff --git a/src/raw_logging.cc b/src/raw_logging.cc
index 5224f19..7a7409b 100644
--- a/src/raw_logging.cc
+++ b/src/raw_logging.cc
@@ -59,8 +59,7 @@
 # include <unistd.h>
 #endif
 
-#if (defined(HAVE_SYSCALL_H) || defined(HAVE_SYS_SYSCALL_H)) && \
-    MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_X_VERSION_10_12
+#if defined(HAVE_SYSCALL_H) || defined(HAVE_SYS_SYSCALL_H)
 # define safe_write(fd, s, len)  syscall(SYS_write, fd, s, len)
 #else
   // Not so safe, but what can you do?
diff --git a/src/utilities.cc b/src/utilities.cc
index 09b96b2..5c88e58 100644
--- a/src/utilities.cc
+++ b/src/utilities.cc
@@ -238,15 +238,8 @@
 }
 
 pid_t GetTID() {
-  // On Linux, and MacOSX prior to 10.12, we try to use gettid(). On
-  // MacOSX 10.12 and later, we use pthread_threadid_np instead, as
-  // syscall is deprecated.
+  // On Linux and MacOSX, we try to use gettid().
 #if defined OS_LINUX || defined OS_MACOSX
-#if MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_12
-  uint64_t tid;
-  pthread_threadid_np(nullptr, &tid);
-  return static_cast<pid_t>(tid);
-#else
 #ifndef __NR_gettid
 #ifdef OS_MACOSX
 #define __NR_gettid SYS_gettid
@@ -268,7 +261,6 @@
     // the value change to "true".
     lacks_gettid = true;
   }
-#endif  // MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_12
 #endif  // OS_LINUX || OS_MACOSX
 
   // If gettid() could not be used, we use one of the following.