[lld-macho][nfc] Convert the mock libSystem.tbd to TBDv4

It doesn't seem like TBDv3 allows for specifying multiple platforms, so I'm
upgrading us to TBDv4. (We need to support multiple platforms in order to test
that we can handle zippered dylibs; that functionality will be added in an
upcoming diff.)

Differential Revision: https://reviews.llvm.org/D101953

lld/test/MachO/Inputs/MacOSX.sdk/usr/lib/libSystem.tbd

diff --git a/lld/test/MachO/Inputs/MacOSX.sdk/usr/lib/libSystem.tbd b/lld/test/MachO/Inputs/MacOSX.sdk/usr/lib/libSystem.tbd
index 427d598..b333678 100644
--- a/lld/test/MachO/Inputs/MacOSX.sdk/usr/lib/libSystem.tbd
+++ b/lld/test/MachO/Inputs/MacOSX.sdk/usr/lib/libSystem.tbd
@@ -1,42 +1,64 @@
---- !tapi-tbd-v3
-archs:            [ x86_64, arm64 ]
-uuids:            [ 'x86_64: 00000000-0000-0000-0000-000000000000', 'arm64: 00000000-0000-0000-0000-000000000010' ]
-platform:         macosx
+--- !tapi-tbd
+tbd-version:      4
+targets:          [ x86_64-macos, arm64-macos ]
+uuids:
+  - target:       x86_64-macos
+    value:        00000000-0000-0000-0000-000000000000
+  - target:       arm64-macos
+    value:        00000000-0000-0000-0000-000000000001
 install-name:     '/usr/lib/libSystem.dylib'
 current-version:  0001.001.1
-exports:
-  - archs:        [ 'x86_64', 'arm64' ]
-    re-exports:   [ '/usr/lib/system/libdyld.dylib',
+reexported-libraries:
+  - targets:      [ x86_64-macos, arm64-macos ]
+    libraries:    [ '/usr/lib/system/libdyld.dylib',
                     '/usr/lib/system/libsystem_c.dylib',
                     '/usr/lib/system/libsystem_m.dylib' ]
---- !tapi-tbd-v3
-archs:            [ x86_64, arm64 ]
-uuids:            [ 'x86_64: 00000000-0000-0000-0000-000000000001', 'arm64: 00000000-0000-0000-0000-000000000011' ]
-platform:         macosx
+--- !tapi-tbd
+tbd-version:      4
+targets:          [ x86_64-macos, arm64-macos ]
+uuids:
+  - target:       x86_64-macos
+    value:        00000000-0000-0000-0000-000000000002
+  - target:       arm64-macos
+    value:        00000000-0000-0000-0000-000000000003
 install-name:     '/usr/lib/system/libdyld.dylib'
 current-version:  0001.001.1
-parent-umbrella:  System
+parent-umbrella:
+  - targets:      [ x86_64-macos, arm64-macos ]
+    umbrella:     System
 exports:
-  - archs:        [ 'x86_64', 'arm64' ]
+  - targets:      [ x86_64-macos, arm64-macos ]
     symbols:      [ dyld_stub_binder, __tlv_bootstrap ]
---- !tapi-tbd-v3
-archs:            [ x86_64, arm64 ]
-uuids:            [ 'x86_64: 00000000-0000-0000-0000-000000000002', 'arm64: 00000000-0000-0000-0000-000000000012' ]
-platform:         macosx
+--- !tapi-tbd
+tbd-version:      4
+targets:          [ x86_64-macos, arm64-macos ]
+uuids:
+  - target:       x86_64-macos
+    value:        00000000-0000-0000-0000-000000000003
+  - target:       arm64-macos
+    value:        00000000-0000-0000-0000-000000000004
 install-name:     '/usr/lib/system/libsystem_c.dylib'
 current-version:  0001.001.1
-parent-umbrella:  System
+parent-umbrella:
+  - targets:      [ x86_64-macos, arm64-macos ]
+    umbrella:     System
 exports:
-  - archs:        [ 'x86_64', 'arm64' ]
+  - targets:      [ x86_64-macos, arm64-macos ]
     symbols:      [ ]
---- !tapi-tbd-v3
-archs:            [ x86_64, arm64 ]
-uuids:            [ 'x86_64: 00000000-0000-0000-0000-000000000003', 'arm64: 00000000-0000-0000-0000-000000000013' ]
-platform:         macosx
+--- !tapi-tbd
+tbd-version:      4
+targets:          [ x86_64-macos, arm64-macos ]
+uuids:
+  - target:       x86_64-macos
+    value:        00000000-0000-0000-0000-000000000004
+  - target:       arm64-macos
+    value:        00000000-0000-0000-0000-000000000005
 install-name:     '/usr/lib/system/libsystem_m.dylib'
 current-version:  0001.001.1
-parent-umbrella:  System
+parent-umbrella:
+  - targets:      [ x86_64-macos, arm64-macos ]
+    umbrella:     System
 exports:
-  - archs:        [ 'x86_64', 'arm64' ]
+  - targets:      [ x86_64-macos, arm64-macos ]
     symbols:      [ ___nan ]
 ...