pw_build: Switch to pw_* target types

This change replaces the implicit overrides of the default GN target
types in BUILDCONFIG.gn with explicit pw_* versions. This is done to
allow Pigweed to build within larger GN projects without modifying their
BUILDCONFIG files.

Change-Id: I1d1e41d5e9bde8fe076f7031f3c2b98b9630ff70
diff --git a/pw_minimal_cpp_stdlib/BUILD.gn b/pw_minimal_cpp_stdlib/BUILD.gn
index 3cbe163..8e80e8f 100644
--- a/pw_minimal_cpp_stdlib/BUILD.gn
+++ b/pw_minimal_cpp_stdlib/BUILD.gn
@@ -12,6 +12,7 @@
 # License for the specific language governing permissions and limitations under
 # the License.
 
+import("$dir_pw_build/target_types.gni")
 import("$dir_pw_docgen/docs.gni")
 import("$dir_pw_unit_test/test.gni")
 
@@ -23,7 +24,7 @@
   cflags = [ "-nostdinc++" ]
 }
 
-source_set("pw_minimal_cpp_stdlib") {
+pw_source_set("pw_minimal_cpp_stdlib") {
   public_configs = [ ":include_dirs" ]
   configs = [ ":no_cpp_includes" ]
   public = [