[distcc-support] Improve consistency, refactoring

* CMake deduces the path to some tools (ld, nm, objdump, ranlib, and
  strip) from the path to the compiler.  When the compiler is distcc, it
  picks up the generic paths in /usr/bin instead of the one in the Xcode
  being used, so set them explicitly in that case.

* Factor out the distcc command goop to be used for all cmake --build
  invocations.

Author: Dave Abrahams

utils/build-script-impl

@@ -1496,6 +1496,24 @@ eval COMMON_CMAKE_OPTIONS=(${COMMON_CMAKE_OPTIONS})
 eval EXTRA_CMAKE_OPTIONS=(${EXTRA_CMAKE_OPTIONS})
 eval BUILD_ARGS=(${BUILD_ARGS})
 
+if [[ -n "${DISTCC}" ]]; then
+    if [[ "$(uname -s)" == "Darwin" ]] ; then
+        # These are normally deduced by CMake, but when the compiler is set to
+        # distcc which is installed elsewhere, we need to set them explicitly.
+        COMMON_CMAKE_OPTIONS=(
+            "${COMMON_CMAKE_OPTIONS[@]}" "-DCMAKE_AR=$(xcrun_find_tool ar)"
+            "-DCMAKE_LINKER=$(xcrun_find_tool ld)"
+            "-DCMAKE_NM=$(xcrun_find_tool nm)"
+            "-DCMAKE_OBJDUMP=$(xcrun_find_tool objdump)"
+            "-DCMAKE_RANLIB=$(xcrun_find_tool ranlib)"
+            "-DCMAKE_STRIP=$(xcrun_find_tool strip)"
+        )
+    fi
+fi
+
+eval CMAKE_BUILD=("${DISTCC_PUMP}" "${CMAKE}" "--build")
+
+
 if [[ "${CMAKE_GENERATOR}" == "Xcode" ]]; then
     BUILD_TARGET_FLAG="-target"
 fi
@@ -2485,10 +2503,10 @@ for host in "${ALL_HOSTS[@]}"; do
 
                 # Xcode can't restart itself if it turns out we need to reconfigure.
                 # Do an advance build to handle that.
-                call ${DISTCC_PUMP} "${CMAKE}" --build "${build_dir}" $(cmake_config_opt ${product})
+                call "${CMAKE_BUILD[@]}" "${build_dir}" $(cmake_config_opt ${product})
             fi
 
-            call ${DISTCC_PUMP} "${CMAKE}" --build "${build_dir}" $(cmake_config_opt ${product}) -- "${BUILD_ARGS[@]}" ${build_targets[@]}
+            call "${CMAKE_BUILD[@]}" "${build_dir}" $(cmake_config_opt ${product}) -- "${BUILD_ARGS[@]}" ${build_targets[@]}
         fi
     done
 done
@@ -2728,11 +2746,11 @@ for host in "${ALL_HOSTS[@]}"; do
 
         trap "tests_busted ${product} ''" ERR
         build_dir=$(build_directory ${host} ${product})
-        build_cmd=("${CMAKE}" --build "${build_dir}" $(cmake_config_opt ${product}) -- "${BUILD_ARGS[@]}")
+        build_cmd=("${CMAKE_BUILD[@]}" "${build_dir}" $(cmake_config_opt ${product}) -- "${BUILD_ARGS[@]}")
 
         if [[ "${executable_target}" != "" ]]; then
             echo "--- Building tests for ${product} ---"
-            call ${DISTCC_PUMP} "${build_cmd[@]}" ${BUILD_TARGET_FLAG} "${executable_target}"
+            call "${build_cmd[@]}" ${BUILD_TARGET_FLAG} "${executable_target}"
         fi
 
         # We can only run tests built for the host machine, because
@@ -3014,7 +3032,7 @@ for host in "${ALL_HOSTS[@]}"; do
         echo "--- Installing ${product} ---"
         build_dir=$(build_directory ${host} ${product})
 
-        call env DESTDIR="${host_install_destdir}" "${CMAKE}" --build "${build_dir}" -- ${INSTALL_TARGETS}
+        call env DESTDIR="${host_install_destdir}" "${CMAKE_BUILD[@]}" "${build_dir}" -- ${INSTALL_TARGETS}
     done
 
     if [[ "${DARWIN_INSTALL_EXTRACT_SYMBOLS}" ]] && [[ $(host_has_darwin_symbols ${host}) ]]; then