Add CARES_BUILD_TOOLS CMake option (#214)

Add ability to exclude building of tools (adig, ahost, acountry) in CMake.  This should also close #200.

Fix By: Ruslan Baratov (@ruslo)
Bug: #200

CMakeLists.txt

@@ -33,6 +33,7 @@ OPTION (CARES_SHARED     "Build as a shared library"
 OPTION (CARES_INSTALL    "Create installation targets (chain builders may want to disable this)" ON)
 OPTION (CARES_STATIC_PIC "Build the static library as PIC (position independent)"                OFF)
 OPTION (CARES_BUILD_TESTS "Build and run tests"                                                  OFF)
+OPTION (CARES_BUILD_TOOLS "Build tools"                                                          ON)
 
 # allow linking against the static runtime library in msvc
 IF (MSVC)
@@ -668,29 +669,30 @@ ENDIF ()
 SET (CARES_FOUND 1 CACHE INTERNAL "CARES LIBRARY FOUND")
 SET (CARES_LIBRARIES ${PROJECT_NAME}::cares CACHE INTERNAL "CARES LIBRARIES")
 
-
-# Build ahost
-ADD_EXECUTABLE (ahost ahost.c ${SAMPLESOURCES})
-TARGET_COMPILE_DEFINITIONS (ahost PRIVATE HAVE_CONFIG_H=1)
-TARGET_LINK_LIBRARIES (ahost PRIVATE ${PROJECT_NAME})
-IF (CARES_INSTALL)
-	INSTALL (TARGETS ahost ${TARGETS_INST_DEST})
-ENDIF ()
+IF (CARES_BUILD_TOOLS)
+	# Build ahost
+	ADD_EXECUTABLE (ahost ahost.c ${SAMPLESOURCES})
+	TARGET_COMPILE_DEFINITIONS (ahost PRIVATE HAVE_CONFIG_H=1)
+	TARGET_LINK_LIBRARIES (ahost PRIVATE ${PROJECT_NAME})
+	IF (CARES_INSTALL)
+		INSTALL (TARGETS ahost ${TARGETS_INST_DEST})
+	ENDIF ()
 
 
-# Build adig
-ADD_EXECUTABLE (adig adig.c ${SAMPLESOURCES})
-TARGET_COMPILE_DEFINITIONS (adig PRIVATE HAVE_CONFIG_H=1)
-TARGET_LINK_LIBRARIES (adig PRIVATE ${PROJECT_NAME})
-IF (CARES_INSTALL)
-	INSTALL (TARGETS adig ${TARGETS_INST_DEST})
-ENDIF ()
+	# Build adig
+	ADD_EXECUTABLE (adig adig.c ${SAMPLESOURCES})
+	TARGET_COMPILE_DEFINITIONS (adig PRIVATE HAVE_CONFIG_H=1)
+	TARGET_LINK_LIBRARIES (adig PRIVATE ${PROJECT_NAME})
+	IF (CARES_INSTALL)
+		INSTALL (TARGETS adig ${TARGETS_INST_DEST})
+	ENDIF ()
 
 
-# Build acountry
-ADD_EXECUTABLE (acountry acountry.c ${SAMPLESOURCES})
-TARGET_COMPILE_DEFINITIONS (acountry PRIVATE HAVE_CONFIG_H=1)
-TARGET_LINK_LIBRARIES (acountry PRIVATE ${PROJECT_NAME})
-IF (CARES_INSTALL)
-	INSTALL (TARGETS acountry ${TARGETS_INST_DEST})
+	# Build acountry
+	ADD_EXECUTABLE (acountry acountry.c ${SAMPLESOURCES})
+	TARGET_COMPILE_DEFINITIONS (acountry PRIVATE HAVE_CONFIG_H=1)
+	TARGET_LINK_LIBRARIES (acountry PRIVATE ${PROJECT_NAME})
+	IF (CARES_INSTALL)
+		INSTALL (TARGETS acountry ${TARGETS_INST_DEST})
+	ENDIF ()
 ENDIF ()