Add install target, rename lib to 'romulus-m'

Romulus-M/CMakeLists.txt

@@ -5,4 +5,5 @@ set(SRC
     skinny_reference.c
 )
 
-add_library(romulus SHARED ${SRC})
+add_library(romulus-m SHARED ${SRC})
+install(TARGETS romulus-m)

Romulus-M/export.h

@@ -4,6 +4,8 @@
  * This header defines a cross-platform EXPORT macro in order to allow us to
  * build this reference implementation as a library.
  */
+#pragma once
+
 #ifdef _WIN32
 #define EXPORT __declspec(dllexport)
 #else