Fix iOS / Android CMake builds (#5482)

* cmake: Simplify usage of option

boolean OFF is the default value:
https://cmake.org/cmake/help/latest/command/option.html

* Fix iOS / Android CMake builds

closes #4437

CMakeLists.txt

@@ -304,15 +304,23 @@ if(ENABLE_SPIRV_TOOLS_INSTALL)
   endmacro()
 endif()
 
-# Defaults to OFF if the user didn't set it.
-option(SPIRV_SKIP_EXECUTABLES
-  "Skip building the executable and tests along with the library"
-  ${SPIRV_SKIP_EXECUTABLES})
-option(SPIRV_SKIP_TESTS
-  "Skip building tests along with the library" ${SPIRV_SKIP_TESTS})
-if ("${SPIRV_SKIP_EXECUTABLES}")
+# Currently iOS and Android are very similar.
+# They both have their own packaging (APP/APK).
+# Which makes regular executables/testing problematic.
+#
+# Currently the only deliverables for these platforms are
+# libraries (either STATIC or SHARED).
+#
+# Furthermore testing is equally problematic.
+if (IOS OR ANDROID)
+  set(SPIRV_SKIP_EXECUTABLES ON)
+endif()
+
+option(SPIRV_SKIP_EXECUTABLES "Skip building the executable and tests along with the library")
+if (SPIRV_SKIP_EXECUTABLES)
   set(SPIRV_SKIP_TESTS ON)
 endif()
+option(SPIRV_SKIP_TESTS "Skip building tests along with the library")
 
 # Defaults to ON.  The checks can be time consuming.
 # Turn off if they take too long.

source/CMakeLists.txt

@@ -418,12 +418,6 @@ if("${CMAKE_SYSTEM_NAME}" STREQUAL "Linux")
   endif()
 endif()
 
-if (ANDROID)
-    foreach(target ${SPIRV_TOOLS_TARGETS})
-        target_link_libraries(${target} PRIVATE android log)
-    endforeach()
-endif()
-
 if(ENABLE_SPIRV_TOOLS_INSTALL)
   install(TARGETS ${SPIRV_TOOLS_TARGETS} EXPORT ${SPIRV_TOOLS}Targets)
   export(EXPORT ${SPIRV_TOOLS}Targets FILE ${SPIRV_TOOLS}Target.cmake)