file: Restore error capture in undocumented READ_ELF mode

Revise the error message added by commit 115ff6a347 (cmELF: Include the
ELF parsing code unconditionally, 2021-06-17, v3.22.0-rc1~557^2) to
honor the `CAPTURE_ERROR` option.  This is needed by the call site in
`BundleUtilities` to suppress errors on non-ELF files.

Fixes: #23074

Source/cmFileCommand.cxx

@@ -1213,9 +1213,14 @@ bool HandleReadElfCommand(std::vector<std::string> const& args,
 
   cmELF elf(fileNameArg.c_str());
   if (!elf) {
-    status.SetError(cmStrCat("READ_ELF given FILE \"", fileNameArg,
-                             "\" that is not a valid ELF file."));
-    return false;
+    if (arguments.Error.empty()) {
+      status.SetError(cmStrCat("READ_ELF given FILE:\n  ", fileNameArg,
+                               "\nthat is not a valid ELF file."));
+      return false;
+    }
+    status.GetMakefile().AddDefinition(arguments.Error,
+                                       "not a valid ELF file");
+    return true;
   }
 
   if (!arguments.RPath.empty()) {

Tests/RunCMake/file/READ_ELF-stderr.txt

@@ -1,2 +1,19 @@
-.*file READ_ELF must be called with at least three additional arguments\.
-.*file READ_ELF given FILE "XXX" that does not exist\.
+^CMake Error at READ_ELF.cmake:1 \(file\):
+  file READ_ELF must be called with at least three additional arguments\.
+Call Stack \(most recent call first\):
+  CMakeLists.txt:[0-9]+ \(include\)
++
+CMake Error at READ_ELF.cmake:2 \(file\):
+  file READ_ELF given FILE "XXX" that does not exist\.
+Call Stack \(most recent call first\):
+  CMakeLists.txt:[0-9]+ \(include\)
++
+CMake Error at READ_ELF.cmake:4 \(file\):
+  file READ_ELF given FILE:
+
+    [^
+]*/Tests/RunCMake/file/READ_ELF.cmake
+
+  that is not a valid ELF file\.
+Call Stack \(most recent call first\):
+  CMakeLists.txt:[0-9]+ \(include\)$

Tests/RunCMake/file/READ_ELF.cmake

@@ -1,2 +1,4 @@
 file(READ_ELF XXX)
 file(READ_ELF XXX RPATH YYY)
+file(READ_ELF ${CMAKE_CURRENT_LIST_FILE} RPATH YYY CAPTURE_ERROR err)
+file(READ_ELF ${CMAKE_CURRENT_LIST_FILE} RPATH YYY)