build instructions fail

[donhatch]

README.txt says "To build locally run make build".

When I try that on Ubuntu 24.16, it fails with output:

cmake -S . -B build -GNinja -DCMAKE_BUILD_TYPE=Debug -DCMAKE_EXPORT_COMPILE_COMMANDS=On -DCPPTRACE_UNWIND_WITH_LIBUNWIND=On
-- Cpptrace auto config: Using libdwarf for symbols
-- Cpptrace auto config: Using cxxabi for demangling
-- ZSTD VERSION: 1.5.6
-- CMAKE_INSTALL_PREFIX: /usr/local
-- CMAKE_INSTALL_LIBDIR: lib
-- ZSTD_LEGACY_SUPPORT not defined!
-- ZSTD_MULTITHREAD_SUPPORT is enabled
-- Building dwarfgen    ... OFF
-- Building dwarfexample... OFF
-- Building api tests   ... 
-- HAVE_UINTPTR_T 1: uintptr_t defined in stdint.h... YES
-- uintptr_t value considered NO 
-- HAVE_INTPTR_T 1: intptr_t defined in stdint.h... YES
-- intptr_t value considered NO 
-- ENABLE_DECOMPRESSION : ON
-- Found libzstd           : TRUE
-- Found zlib              : TRUE
-- Build with zlib and zstd: TRUE
-- CMAKE_SIZEOF_VOID_P ... : 8
-- Compiler warning options... NO
-- Install prefix ... /usr/local
-- Configuring done (0.4s)
CMake Error: The following variables are used in this project, but they are set to NOTFOUND.
Please set them or make sure they are set and tested correctly in the CMake files:
/home/donhatch/gitrepos/glibc-tools/build/_deps/cpptrace-src/LIBUNWIND_INCLUDE_DIRS
   used as include directory in directory /home/donhatch/gitrepos/glibc-tools/build/_deps/cpptrace-src

-- Generating done (0.0s)
CMake Generate step failed.  Build files cannot be regenerated correctly.
make: *** [Makefile:10: build/configured-debug] Error 1

[mattgodbolt]

Hi; did you install the dependencies, you'll need libunwind too (it's not that clear in the README but we say "Cpptrace depends on libdwarf, zlib, zstd, and is configured to use libunwind."