cmake: don't define ENABLE_NEON flags in non-cross-compiling mode

- NEON / ANDROID_ARM_NEON are toolchain-specific flags
- they are usually not defined for native builds
- let work CPU_BASELINE=DETECT properly

CMakeLists.txt

@@ -486,7 +486,7 @@ OCV_OPTION(OPENCV_ENABLE_MEMORY_SANITIZER "Better support for memory/address san
 OCV_OPTION(ENABLE_OMIT_FRAME_POINTER  "Enable -fomit-frame-pointer for GCC"                      ON   IF CV_GCC )
 OCV_OPTION(ENABLE_POWERPC             "Enable PowerPC for GCC"                                   ON   IF (CV_GCC AND CMAKE_SYSTEM_PROCESSOR MATCHES powerpc.*) )
 OCV_OPTION(ENABLE_FAST_MATH           "Enable compiler options for fast math optimizations on FP computations (not recommended)" OFF)
-if(NOT IOS)  # Use CPU_BASELINE instead
+if(NOT IOS AND CMAKE_CROSSCOMPILING)  # Use CPU_BASELINE instead
 OCV_OPTION(ENABLE_NEON                "Enable NEON instructions"                                 (NEON OR ANDROID_ARM_NEON OR AARCH64) IF (CV_GCC OR CV_CLANG) AND (ARM OR AARCH64 OR IOS) )
 OCV_OPTION(ENABLE_VFPV3               "Enable VFPv3-D32 instructions"                            OFF  IF (CV_GCC OR CV_CLANG) AND (ARM OR AARCH64 OR IOS) )
 endif()