Add profiling support to AIX

AIX ld needs special option to merge objects with profiling. Also,
profiler_builtins should include builtins for AIX from compiler-rt.

compiler/rustc_codegen_ssa/src/back/linker.rs

@@ -1631,7 +1631,9 @@ fn no_gc_sections(&mut self) {
 
     fn optimize(&mut self) {}
 
-    fn pgo_gen(&mut self) {}
+    fn pgo_gen(&mut self) {
+        self.cmd.arg("-bdbg:namedsects:ss");
+    }
 
     fn control_flow_guard(&mut self) {}
 

library/profiler_builtins/build.rs

@@ -26,6 +26,7 @@ fn main() {
         "InstrProfilingMerge.c",
         "InstrProfilingMergeFile.c",
         "InstrProfilingNameVar.c",
+        "InstrProfilingPlatformAIX.c",
         "InstrProfilingPlatformDarwin.c",
         "InstrProfilingPlatformFuchsia.c",
         "InstrProfilingPlatformLinux.c",