turn of PCH with clazy (#1432)

* fix brew warning in CI.

github hosted mac runners include ninja.

* turn off pch with clazy.

although we never noticed any problems with pch enabled, the clazy
recommendation is to turn off PCH when using clazy.

Author: tsteven4

tools/build_extra_tests.sh

@@ -46,7 +46,7 @@ rm -rf bld-clazy
 mkdir bld-clazy
 pushd bld-clazy
 export CLAZY_CHECKS=level0,level1,no-non-pod-global-static,no-qstring-ref
-cmake -DCMAKE_CXX_COMPILER=clazy -DCMAKE_BUILD_TYPE=Debug -G Ninja "${SOURCE_DIR}"
+cmake -DCMAKE_CXX_COMPILER=clazy -DCMAKE_BUILD_TYPE=Debug -DGPSBABEL_ENABLE_PCH=OFF -G Ninja "${SOURCE_DIR}"
 cmake --build . 2>&1 | tee clazy.log
 if grep -- '-Wclazy' clazy.log; then
   exit 1