[NFC][compiler-rt][hwasan] Rename InitPrctl to InitializeOsSupport

The new name is something less linux-y and more platform generic. Once we
finalize the tagged pointer ABI in zircon, we will do the appropriate check
for fuchsia to see that TBI is enabled.

Differential Revision: https://reviews.llvm.org/D105667

compiler-rt/lib/hwasan/hwasan.cpp

@@ -275,7 +275,7 @@ static void InitLoadedGlobals() {
 static void InitInstrumentation() {
   if (hwasan_instrumentation_inited) return;
 
-  InitPrctl();
+  InitializeOsSupport();
 
   if (!InitShadow()) {
     Printf("FATAL: HWAddressSanitizer cannot mmap the shadow memory.\n");

compiler-rt/lib/hwasan/hwasan.h

@@ -102,7 +102,7 @@ extern bool hwasan_init_is_running;
 extern int hwasan_report_count;
 
 bool InitShadow();
-void InitPrctl();
+void InitializeOsSupport();
 void InitThreads();
 void InitializeInterceptors();
 

compiler-rt/lib/hwasan/hwasan_linux.cpp

@@ -116,7 +116,7 @@ static void InitializeShadowBaseAddress(uptr shadow_size_bytes) {
       FindDynamicShadowStart(shadow_size_bytes);
 }
 
-void InitPrctl() {
+void InitializeOsSupport() {
 #define PR_SET_TAGGED_ADDR_CTRL 55
 #define PR_GET_TAGGED_ADDR_CTRL 56
 #define PR_TAGGED_ADDR_ENABLE (1UL << 0)