Include InkAPITest.cc only if BUILD_REGRESSION_TESTING is on

Author: maskit

src/api/CMakeLists.txt

@@ -16,7 +16,10 @@
 #######################
 
 # plugin api *only*
-add_library(tsapi SHARED InkAPI.cc InkAPIInternal.cc InkIOCoreAPI.cc InkAPITest.cc)
+add_library(tsapi SHARED InkAPI.cc InkAPIInternal.cc InkIOCoreAPI.cc)
+if(BUILD_REGRESSION_TESTING)
+  target_sources(tsapi PRIVATE InkAPITest.cc)
+endif()
 add_library(ts::tsapi ALIAS tsapi)
 
 set(TSAPI_PUBLIC_HEADERS ${PROJECT_SOURCE_DIR}/include/ts/ts.h ${PROJECT_SOURCE_DIR}/include/ts/remap.h