CI: Configure macOS build as per updated devguide recommendations (#105533)

Author: erlend-aasland

.github/workflows/build.yml

@@ -235,9 +235,8 @@ jobs:
       run: brew install pkg-config [email protected] xz gdbm tcl-tk
     - name: Configure CPython
       run: |
-        CFLAGS="-I$(brew --prefix gdbm)/include -I$(brew --prefix xz)/include" \
-        LDFLAGS="-L$(brew --prefix gdbm)/lib -I$(brew --prefix xz)/lib" \
-        PKG_CONFIG_PATH="$(brew --prefix tcl-tk)/lib/pkgconfig" \
+        GDBM_CFLAGS="-I$(brew --prefix gdbm)/include" \
+        GDBM_LIBS="-L$(brew --prefix gdbm)/lib -lgdbm" \
         ./configure \
           --config-cache \
           --with-pydebug \