Refactor simd/conf.rb - conditions to enable

See the results of `have_type` and `try_compile` in addition to
`have_header` for NEON as well as x86_64.  The former results were
just ignored, and `HAVE_TYPE_` macros are unused too.

Author: nobu

ext/json/ext/simd/conf.rb

@@ -1,8 +1,8 @@
 case RbConfig::CONFIG['host_cpu']
 when /^(arm|aarch64)/
   # Try to compile a small program using NEON instructions
-  if have_header('arm_neon.h')
-    have_type('uint8x16_t', headers=['arm_neon.h']) && try_compile(<<~'SRC')
+  if have_header('arm_neon.h') &&
+     have_type('uint8x16_t', headers=['arm_neon.h']) && try_compile(<<~'SRC')
       #include <arm_neon.h>
       int main(int argc, char **argv) {
           uint8x16_t test = vdupq_n_u8(32);
@@ -13,7 +13,8 @@
     $defs.push("-DJSON_ENABLE_SIMD")
   end
 when /^(x86_64|x64)/
-  if have_header('x86intrin.h') && have_type('__m128i', headers=['x86intrin.h']) && try_compile(<<~'SRC')
+  if have_header('x86intrin.h') &&
+     have_type('__m128i', headers=['x86intrin.h']) && try_compile(<<~'SRC')
       #include <x86intrin.h>
       int main(int argc, char **argv) {
           __m128i test = _mm_set1_epi8(32);