Set a reasonable default for SWIFT_INSTALL_COMPONENTS

Previously, build-script-impl would set this to "" by default, resulting
in nothing being installed with --install-swift unless you explicitly
set --swift-install-components as well.  Now we defer to cmake by
default.

On the cmake side, change the default value to exclude
* dev - uses a lot of disk space and usually not something you want to
  install into a toolchain
* clang-resource-dir-symlink & clang-builtin-headers-in-clang-resource-dir -
  these are mutually exclusive with clang-builtin-headers
* sourcekit inproc/xpc - these are currently mutually exclusive, so pick
  the best one for the current platform.

Author: benlangmuir

cmake/modules/SwiftComponents.cmake

@@ -67,10 +67,25 @@
 set(_SWIFT_DEFINED_COMPONENTS
   "autolink-driver;compiler;clang-builtin-headers;clang-resource-dir-symlink;clang-builtin-headers-in-clang-resource-dir;stdlib;stdlib-experimental;sdk-overlay;parser-lib;editor-integration;tools;testsuite-tools;toolchain-dev-tools;dev;license;sourcekit-xpc-service;sourcekit-inproc;swift-remote-mirror;swift-remote-mirror-headers")
 
+# The default install components include all of the defined components, except
+# for the following exceptions.
+set(_SWIFT_DEFAULT_COMPONENTS "${_SWIFT_DEFINED_COMPONENTS}")
+# 'dev' takes up a lot of disk space and isn't part of a normal toolchain.
+list(REMOVE_ITEM _SWIFT_DEFAULT_COMPONENTS "dev")
+# These clang header options conflict with 'clang-builtin-headers'.
+list(REMOVE_ITEM _SWIFT_DEFAULT_COMPONENTS "clang-resource-dir-symlink")
+list(REMOVE_ITEM _SWIFT_DEFAULT_COMPONENTS "clang-builtin-headers-in-clang-resource-dir")
+# The sourcekit install variants are currently mutually exclusive.
+if(${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
+  list(REMOVE_ITEM _SWIFT_DEFAULT_COMPONENTS "sourcekit-inproc")
+else()
+  list(REMOVE_ITEM _SWIFT_DEFAULT_COMPONENTS "sourcekit-xpc-service")
+endif()
+
 macro(swift_configure_components)
   # Set the SWIFT_INSTALL_COMPONENTS variable to the default value if it is not passed in via -D
-  set(SWIFT_INSTALL_COMPONENTS "${_SWIFT_DEFINED_COMPONENTS}" CACHE STRING
-    "A semicolon-separated list of components to install ${_SWIFT_DEFINED_COMPONENTS}")
+  set(SWIFT_INSTALL_COMPONENTS "${_SWIFT_DEFAULT_COMPONENTS}" CACHE STRING
+    "A semicolon-separated list of components to install from the set ${_SWIFT_DEFINED_COMPONENTS}")
 
   foreach(component ${_SWIFT_DEFINED_COMPONENTS})
     string(TOUPPER "${component}" var_name_piece)

utils/build-script-impl

@@ -2290,7 +2290,6 @@ for host in "${ALL_HOSTS[@]}"; do
                     -DSWIFT_BUILD_EXTERNAL_PERF_TESTSUITE:BOOL=$(true_false "${build_external_perf_testsuite_this_time}")
                     -DSWIFT_BUILD_EXAMPLES:BOOL=$(true_false "${BUILD_SWIFT_EXAMPLES}")
                     -DSWIFT_INCLUDE_TESTS:BOOL=$(true_false "${build_tests_this_time}")
-                    -DSWIFT_INSTALL_COMPONENTS:STRING="${SWIFT_INSTALL_COMPONENTS}"
                     -DSWIFT_EMBED_BITCODE_SECTION:BOOL=$(true_false "${EMBED_BITCODE_SECTION}")
                     -DSWIFT_TOOLS_ENABLE_LTO:STRING="${SWIFT_TOOLS_ENABLE_LTO}"
                     -DSWIFT_BUILD_RUNTIME_WITH_HOST_COMPILER:BOOL=$(true_false "${BUILD_RUNTIME_WITH_HOST_COMPILER}")
@@ -2361,6 +2360,13 @@ for host in "${ALL_HOSTS[@]}"; do
                     )
                 fi
 
+                if [ "${SWIFT_INSTALL_COMPONENTS}" ] ; then
+                    cmake_options=(
+                        "${cmake_options[@]}"
+                        -DSWIFT_INSTALL_COMPONENTS:STRING="${SWIFT_INSTALL_COMPONENTS}"
+                    )
+                fi
+
                 if contains_product "lldb" ; then
                     lldb_build_dir=$(build_directory ${host} lldb)
                     cmake_options=(