NFCI: update debug-names-types test to use an output file unique to the test

This makes it work in environments where the test is running in a write-protected
current directory. Updated similarly to other such tests, like
https://github.com/llvm/llvm-project/blob/8bd06d5b65845e5e01dd899a2deb773580460b89/llvm/test/tools/llvm-dwp/X86/absolute_paths.test#L3.

Author: krasimirgg

llvm/test/DebugInfo/X86/debug-names-types.ll

@@ -5,7 +5,7 @@
 ; RUN: llc -mtriple=x86_64 -generate-type-units -dwarf-version=5 -filetype=obj %s -o %t
 ; RUN: llvm-dwarfdump -debug-info -debug-names %t | FileCheck %s
 
-; RUN: llc -mtriple=x86_64 -generate-type-units -dwarf-version=5 -filetype=obj -split-dwarf-file=mainTypes.dwo --split-dwarf-output=mainTypes.dwo %s -o %t
+; RUN: llc -mtriple=x86_64 -generate-type-units -dwarf-version=5 -filetype=obj -split-dwarf-file=%t.mainTypes.dwo --split-dwarf-output=%t.mainTypes.dwo %s -o %t
 ; RUN: llvm-readelf --sections %t | FileCheck %s --check-prefixes=CHECK-SPLIT
 
 ; CHECK-SPLIT-NOT: .debug_names