[llvm-profgen] Ignore inline frames with an emtpy function name (#66678)

Broken debug information can give empty names for an inlined frame, e.g,
```

0x1d605c68: ryKeyINS7_17SmartCounterTypesEEESt10shared_ptrINS7_15AsyncCacheValueIS9_EEESaIhESt6atomicEEE9fetch_subElSt12memory_order at   Filename: edata.h
  Function start filename: edata.h
  Function start line: 266
  Function start address: 0x1d605c68
  Line: 267
  Column: 0
 (inlined by)  at   Filename: edata.h
  Function start filename: edata.h
  Function start line: 274
  Function start address: 0x1d605c68
  Line: 275
  Column: 0
 (inlined by) _EEEmmEv at   Filename: arena.c
  Function start filename: arena.c
  Function start line: 1303
  Line: 1308
  Column: 0
```

This patch avoids creating a sample context with an empty function name
by stopping tracking at that frame. This prevents a hash failure that
leads to an ICE, where empty context serves at an empty key for the
underlying MapVector
https://github.com/llvm/llvm-project/blob/7624de5beae2f142abfdb3e32a63c263a586d768/llvm/lib/ProfileData/SampleProfWriter.cpp#L261