Add regression test

src/test/ui/panics/panic-short-backtrace-windows-x86_64.rs

+// Regression test for #87481: short backtrace formatting cut off the entire stack trace.
+
+// Codegen-units is specified here so that we can replicate a typical rustc invocation which
+// is not normally limited to 1 CGU. This is important so that the `__rust_begin_short_backtrace`
+// and `__rust_end_short_backtrace` symbols are not marked internal to the CGU and thus will be
+// named in the symbol table.
+// compile-flags: -O -Ccodegen-units=8
+
+// run-fail
+// check-run-results
+// exec-env:RUST_BACKTRACE=1
+
+// Backtraces are pretty broken in general on i686-pc-windows-msvc (#62897).
+// only-x86_64-pc-windows-msvc
+
+fn main() {
+    a();
+}
+
+// Make these no_mangle so dbghelp.dll can figure out the symbol names.
+
+#[no_mangle]
+#[inline(never)]
+fn a() {
+    b();
+}
+
+#[no_mangle]
+#[inline(never)]
+fn b() {
+    c();
+}
+
+#[no_mangle]
+#[inline(never)]
+fn c() {
+    d();
+}
+
+#[no_mangle]
+#[inline(never)]
+fn d() {
+    panic!("d was called");
+}

src/test/ui/panics/panic-short-backtrace-windows-x86_64.run.stderr

+thread 'main' panicked at 'd was called', $DIR/panic-short-backtrace-windows-x86_64.rs:43:5
+stack backtrace:
+note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.