Speed up the GenerateExportHeader unit test (#14453).

Instead of running many small tests with many cmake projects, simply
compare the generated export header against a reference.

Remove the helper macros and the try_compiles which are duplicates
of the library build tests.

Tests/Module/GenerateExportHeader/reference/WinEmpty/libshared_export.h

@@ -0,0 +1,41 @@
+
+#ifndef LIBSHARED_EXPORT_H
+#define LIBSHARED_EXPORT_H
+
+#ifdef LIBSHARED_STATIC_DEFINE
+#  define LIBSHARED_EXPORT
+#  define LIBSHARED_NO_EXPORT
+#else
+#  ifndef LIBSHARED_EXPORT
+#    ifdef libshared_EXPORTS
+        /* We are building this library */
+#      define LIBSHARED_EXPORT __declspec(dllexport)
+#    else
+        /* We are using this library */
+#      define LIBSHARED_EXPORT __declspec(dllimport)
+#    endif
+#  endif
+
+#  ifndef LIBSHARED_NO_EXPORT
+#    define LIBSHARED_NO_EXPORT
+#  endif
+#endif
+
+#ifndef LIBSHARED_DEPRECATED
+#  define LIBSHARED_DEPRECATED
+#endif
+
+#ifndef LIBSHARED_DEPRECATED_EXPORT
+#  define LIBSHARED_DEPRECATED_EXPORT LIBSHARED_EXPORT LIBSHARED_DEPRECATED
+#endif
+
+#ifndef LIBSHARED_DEPRECATED_NO_EXPORT
+#  define LIBSHARED_DEPRECATED_NO_EXPORT LIBSHARED_NO_EXPORT LIBSHARED_DEPRECATED
+#endif
+
+#define DEFINE_NO_DEPRECATED 0
+#if DEFINE_NO_DEPRECATED
+# define LIBSHARED_NO_DEPRECATED
+#endif
+
+#endif

Tests/Module/GenerateExportHeader/reference/WinEmpty/libstatic_export.h

@@ -0,0 +1,41 @@
+
+#ifndef LIBSTATIC_EXPORT_H
+#define LIBSTATIC_EXPORT_H
+
+#ifdef LIBSTATIC_STATIC_DEFINE
+#  define LIBSTATIC_EXPORT
+#  define LIBSTATIC_NO_EXPORT
+#else
+#  ifndef LIBSTATIC_EXPORT
+#    ifdef libstatic_EXPORTS
+        /* We are building this library */
+#      define LIBSTATIC_EXPORT
+#    else
+        /* We are using this library */
+#      define LIBSTATIC_EXPORT
+#    endif
+#  endif
+
+#  ifndef LIBSTATIC_NO_EXPORT
+#    define LIBSTATIC_NO_EXPORT
+#  endif
+#endif
+
+#ifndef LIBSTATIC_DEPRECATED
+#  define LIBSTATIC_DEPRECATED
+#endif
+
+#ifndef LIBSTATIC_DEPRECATED_EXPORT
+#  define LIBSTATIC_DEPRECATED_EXPORT LIBSTATIC_EXPORT LIBSTATIC_DEPRECATED
+#endif
+
+#ifndef LIBSTATIC_DEPRECATED_NO_EXPORT
+#  define LIBSTATIC_DEPRECATED_NO_EXPORT LIBSTATIC_NO_EXPORT LIBSTATIC_DEPRECATED
+#endif
+
+#define DEFINE_NO_DEPRECATED 0
+#if DEFINE_NO_DEPRECATED
+# define LIBSTATIC_NO_DEPRECATED
+#endif
+
+#endif