[build-script] Disable pkg-config for Darwin hosts

Author: kastiglione

utils/build-script

@@ -655,9 +655,12 @@ class BuildScriptInvocation(object):
             ]
 
             # Isolate build from the system; Darwin toolchains build against SDKs.
-            args.extra_cmake_options.append(
-                '-DCMAKE_IGNORE_PATH=/usr/lib;/usr/local/lib;/lib'
-            )
+            # For additional isolation, disable pkg-config. Homebrew's pkg-config
+            # prioritizes CommandLineTools paths, resulting in compile errors.
+            args.extra_cmake_options += [
+                '-DCMAKE_IGNORE_PATH=/usr/lib;/usr/local/lib;/lib',
+                '-DPKG_CONFIG_EXECUTABLE=/usr/bin/true',
+            ]
 
         if toolchain.libtool is not None:
             impl_args += [

utils/build-script-impl

@@ -632,17 +632,6 @@ function set_build_options_for_host() {
 
             cmake_os_sysroot="$(xcrun --sdk ${platform} --show-sdk-path)"
 
-            # Customize the CMake `find_*` search paths to search the SDK
-            # sysroot before searching `pkg-config` paths. This prevents compile
-            # failures caused when `pkg-config` returns CommandLineTools paths
-            # instead of Xcode paths.
-            #
-            # These search paths can be user customized either by setting the
-            # `CMAKE_PREFIX_PATH` environment variable, or by setting the same
-            # CMake variable via the command line (`-DCMAKE_PREFIX_PATH`).
-            # See https://cmake.org/cmake/help/latest/command/find_path.html
-            export CMAKE_PREFIX_PATH="${CMAKE_PREFIX_PATH}:${cmake_os_sysroot}/usr"
-
             cmark_cmake_options=(
                 -DCMAKE_C_FLAGS="$(cmark_c_flags ${host})"
                 -DCMAKE_CXX_FLAGS="$(cmark_c_flags ${host})"