Apple M1: Improved handling of paths

Incorporated changes suggested by Kode54 to use the CMake prefix path, instead
of relying on pkg-config directory paths.

Added the prefix paths from the other architectures build to the CMake ignore
path so that CMake doesn't pick up libraries from the wrong architecture if
they are in the user's search path.

BuildMacOSUniversalBinary.py

@@ -42,11 +42,9 @@ DEFAULT_CONFIG = {
     # Build Target (dolphin-emu to just build the emulator and skip the tests)
     "build_target": "ALL_BUILD",
 
-    # Locations to pkg config files for arm and x64 libraries
-    # The default values of these paths are taken from the default
-    # paths used for homebrew
-    "arm64_pkg_config_path":  '/opt/homebrew/lib/pkgconfig',
-    "x86_64_pkg_config_path": '/usr/local/lib/pkgconfig',
+    # Location for CMake to search for files(default is for homebrew
+    "arm64_cmake_prefix":  '/opt/homebrew',
+    "x86_64_cmake_prefix": '/usr/local',
 
     # Locations to qt5 directories for arm and x64 libraries
     # The default values of these paths are taken from the default
@@ -124,10 +122,10 @@ def parse_args(conf=DEFAULT_CONFIG):
 
     for arch in ARCHITECTURES:
         parser.add_argument(
-             '--{}_pkg_config'.format(arch),
-             help="Folder containing .pc files for {} libraries".format(arch),
-             default=conf[arch+"_pkg_config_path"],
-             dest=arch+"_pkg_config_path")
+             '--{}_cmake_prefix'.format(arch),
+             help="Folder for cmake to search for packages".format(arch),
+             default=conf[arch+"_cmake_prefix"],
+             dest=arch+"_cmake_prefix")
 
         parser.add_argument(
              '--{}_qt5_path'.format(arch),
@@ -229,9 +227,17 @@ def build(config):
             os.mkdir(arch)
 
         env = os.environ.copy()
-        env['PKG_CONFIG_PATH'] = config[arch+"_pkg_config_path"]
         env['Qt5_DIR'] = config[arch+"_qt5_path"]
         env['CMAKE_OSX_ARCHITECTURES'] = arch
+        env['CMAKE_PREFIX_PATH'] = config[arch+"_cmake_prefix"]
+
+        # Add the other architecture's prefix path to the ignore path so that
+        # CMake doesn't try to pick up the wrong architecture's libraries when
+        # cross compiling.
+        ignore_path = ""
+        for a in ARCHITECTURES:
+            if a != arch:
+                ignore_path = config[a+"_cmake_prefix"]
 
         subprocess.check_call([
                 'cmake', '../../', '-G', config['generator'],
@@ -239,7 +245,9 @@ def build(config):
                 # System name needs to be specified for CMake to use
                 # the specified CMAKE_SYSTEM_PROCESSOR
                 '-DCMAKE_SYSTEM_NAME=Darwin',
+                '-DCMAKE_PREFIX_PATH='+config[arch+'_cmake_prefix'],
                 '-DCMAKE_SYSTEM_PROCESSOR='+arch,
+                '-DCMAKE_IGNORE_PATH='+ignore_path,
                 '-DCMAKE_OSX_DEPLOYMENT_TARGET='
                 + config[arch+"_mac_os_deployment_target"],
                 '-DMACOS_CODE_SIGNING_IDENTITY='