[MC] Make .pseudo_probe sections deterministic after D91878

MCPseudoProbeSections::emit iterates over MCProbeDivisions and creates sections.
When the map key is MCSymbol *, the iteration order is not stable. The
underlying BumpPtrAllocator largely decreases the flakiness. That said,
the allocations from BumpPtrAllocator may have different orders.
Under tcmalloc, llvm/test/Transforms/SampleProfile/pseudo-probe-emit.ll fails
about 7 times per 1000 runs.

Author: MaskRay

llvm/include/llvm/MC/MCPseudoProbe.h

@@ -55,6 +55,7 @@
 #define LLVM_MC_MCPSEUDOPROBE_H
 
 #include "llvm/ADT/DenseSet.h"
+#include "llvm/ADT/MapVector.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/IR/PseudoProbe.h"
@@ -299,8 +300,7 @@ class MCPseudoProbeSections {
     MCProbeDivisions[FuncSym].addPseudoProbe(Probe, InlineStack);
   }
 
-  // TODO: Sort by getOrdinal to ensure a determinstic section order
-  using MCProbeDivisionMap = std::map<MCSymbol *, MCPseudoProbeInlineTree>;
+  using MCProbeDivisionMap = MapVector<MCSymbol *, MCPseudoProbeInlineTree>;
 
 private:
   // A collection of MCPseudoProbe for each function. The MCPseudoProbes are