Added Emscripten to list of supported systems in CMakeLists.txt (#310)

CMakeLists.txt

diff --git a/CMakeLists.txt b/CMakeLists.txt
index aedc983..b260162 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -108,7 +108,7 @@
       "Target operating system is not specified. "
       "cpuinfo will compile, but cpuinfo_initialize() will always fail.")
   SET(CPUINFO_SUPPORTED_PLATFORM FALSE)
-ELSEIF(NOT CMAKE_SYSTEM_NAME MATCHES "^(Windows|WindowsStore|CYGWIN|MSYS|Darwin|Linux|Android|FreeBSD)$")
+ELSEIF(NOT CMAKE_SYSTEM_NAME MATCHES "^(Windows|WindowsStore|CYGWIN|MSYS|Darwin|Linux|Android|FreeBSD|Emscripten)$")
   IF(${CMAKE_VERSION} VERSION_GREATER_EQUAL "3.14" AND NOT IS_APPLE_OS)
     MESSAGE(WARNING
       "Target operating system \"${CMAKE_SYSTEM_NAME}\" is not supported in cpuinfo. "