meta: add msvc support

since bluelib is already cross-platform, this is mostly just adding
__declspec(dllexport) to the library functions.

rt/CMakeLists.txt

@@ -2,3 +2,5 @@ file(GLOB_RECURSE rt_sources *.c *.h include/ivy/rt/*.h)
 
 add_library(ivy-rt SHARED ${rt_sources})
 target_include_directories(ivy-rt PUBLIC ${CMAKE_CURRENT_SOURCE_DIR}/include/)
+target_link_libraries(ivy-rt ivy-common)
+target_compile_definitions(ivy-rt PRIVATE IVY_EXPORT=1)

rt/include/ivy/rt/runtime.h

@@ -0,0 +1,8 @@
+#ifndef IVY_RT_RUNTIME_H_
+#define IVY_RT_RUNTIME_H_
+
+#include <ivy/misc.h>
+
+IVY_API void placeholder(void);
+
+#endif

rt/runtime.c

@@ -0,0 +1,6 @@
+#include <ivy/rt/runtime.h>
+
+void placeholder(void)
+{
+
+}