Fix compile errors when using clang-x86_64-pc-windows-msvc (#129)

main.cpp

diff --git a/main.cpp b/main.cpp
index b12e5cf..1c927b6 100644
--- a/main.cpp
+++ b/main.cpp
@@ -57,7 +57,7 @@
 #endif
 
 // missing __builtins on windows
-#ifdef _MSC_VER
+#if defined(_MSC_VER) && !defined(__clang__)
 #  include <intrin.h>
 #  define __builtin_popcount __popcnt
 static __forceinline int __builtin_ctz(unsigned x) {

otp_header_parser/otp_header_parse.cpp

diff --git a/otp_header_parser/otp_header_parse.cpp b/otp_header_parser/otp_header_parse.cpp
index 04ead13..00e924c 100644
--- a/otp_header_parser/otp_header_parse.cpp
+++ b/otp_header_parser/otp_header_parse.cpp
@@ -15,7 +15,7 @@
 #include "nlohmann/json.hpp"
 
 // missing __builtins on windows
-#ifdef _MSC_VER
+#if defined(_MSC_VER) && !defined(__clang__)
 #  include <intrin.h>
 #  define __builtin_popcount __popcnt
 static __forceinline int __builtin_ctz(unsigned x) {