pdal: link to libunwind

`pdal` opportunistically linked to LLVM's libunwind on Linux, causing a
runtime dependency on it. Instead let's properly link it to `libunwind`.

Discovered in #169354.

Formula/p/pdal.rb

@@ -4,6 +4,7 @@ class Pdal < Formula
  url "https://github.com/PDAL/PDAL/releases/download/2.7.1/PDAL-2.7.1-src.tar.bz2"
  sha256 "7769aaacfc26daeb559b511c73c241a5e9a2f31e26ef3a736204b83e791c5453"
  license "BSD-3-Clause"
+ revision 1
  head "https://github.com/PDAL/PDAL.git", branch: "master"
 
  # The upstream GitHub repository sometimes creates tags that only include a
@@ -35,22 +36,37 @@ class Pdal < Formula
  depends_on "numpy"
  depends_on "openssl@3"
 
+ on_linux do
+ depends_on "libunwind"
+ end
+
  fails_with gcc: "5" # gdal is compiled with GCC
 
  def install
  # Work around an Xcode 15 linker issue which causes linkage against LLVM's
  # libunwind due to it being present in a library search path.
  ENV.remove "HOMEBREW_LIBRARY_PATHS", Formula["llvm"].opt_lib if DevelopmentTools.clang_build_version >= 1500
 
- system "cmake", ".", *std_cmake_args,
- "-DWITH_LASZIP=TRUE",
- "-DBUILD_PLUGIN_GREYHOUND=ON",
- "-DBUILD_PLUGIN_ICEBRIDGE=ON",
- "-DBUILD_PLUGIN_PGPOINTCLOUD=ON",
- "-DBUILD_PLUGIN_PYTHON=ON",
- "-DBUILD_PLUGIN_SQLITE=ON"
+ args = %w[
+ -DWITH_LASZIP=TRUE
+ -DBUILD_PLUGIN_GREYHOUND=ON
+ -DBUILD_PLUGIN_ICEBRIDGE=ON
+ -DBUILD_PLUGIN_PGPOINTCLOUD=ON
+ -DBUILD_PLUGIN_PYTHON=ON
+ -DBUILD_PLUGIN_SQLITE=ON
+ ]
+ if OS.linux?
+ libunwind = Formula["libunwind"]
+ ENV.append_to_cflags "-I#{libunwind.opt_include}"
+ args += %W[
+ -DLIBUNWIND_INCLUDE_DIR=#{libunwind.opt_include}
+ -DLIBUNWIND_LIBRARY=#{libunwind.opt_lib/shared_library("libunwind")}
+ ]
+ end
+ system "cmake", "-S", ".", "-B", "build", *std_cmake_args, *args
+ system "cmake", "--build", "build"
+ system "cmake", "--install", "build"
 
- system "make", "install"
  rm_rf "test/unit"
  doc.install "examples", "test"
  end