[libFuzzer][MSVC] Enable building libFuzzer with MSVC

Summary:
Enable building libFuzzer with MSVC.

* Don't try to include <endian.h> in FuzzerSHA1.cpp. MSVC
  doesn't have this header, and WINDOWS is always little
  endian (even on ARM)

Subscribers: srhines, mgorny, javed.absar, kristof.beyls

Differential Revision: https://reviews.llvm.org/D56510

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk/lib/fuzzer@351855 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/FuzzerSHA1.cpp b/FuzzerSHA1.cpp
index 99c075f..43e5e78 100644
--- a/FuzzerSHA1.cpp
+++ b/FuzzerSHA1.cpp
@@ -31,7 +31,8 @@
 
 #ifdef __BIG_ENDIAN__
 # define SHA_BIG_ENDIAN
-#elif defined __LITTLE_ENDIAN__
+// Windows is always little endian and MSVC doesn't have <endian.h>
+#elif defined __LITTLE_ENDIAN__ || LIBFUZZER_WINDOWS
 /* override */
 #elif defined __BYTE_ORDER
 # if __BYTE_ORDER__ ==  __ORDER_BIG_ENDIAN__