[llvm] [readtapi] Add Merge functionality (PR #72656)

[Juergen Ributzka via llvm-commits]

================
@@ -0,0 +1,99 @@
+; RUN: rm -rf %t
+; RUN: split-file %s %t
+; RUN: llvm-readtapi -merge %t/i386.tbd %t/x86_64.tbd %t/arm64.tbd --filetype tbd-v5 -o %t/out.tbd -compact 2>&1 | FileCheck %s --allow-empty 
+; RUN: llvm-readtapi -merge %t/i386.tbd %t/x86_64.tbd %t/arm64.tbd --filetype=tbd-v5 --o %t/out.tbd -compact 2>&1 | FileCheck %s --allow-empty 
+; RUN: llvm-readtapi -compare %t/out.tbd %t/expected.tbd 2>&1 | FileCheck %s --allow-empty 
+
+; CHECK-NOT: error 
+; CHECK-NOT: warning
+
+;--- expected.tbd
----------------
ributzka wrote:

Could this be pretty printed?

https://github.com/llvm/llvm-project/pull/72656