tests: Test extern'd globals on MacOS with the Apple Archiver

This forces the use of the Apple archiver, since that archiver doesn't
add extern'd variables to the symbol table automatically, and instead
requires that ranlib be used. A native file is used to ensure that
Apple's ar is used even in the presence of llvm or gcc in the path with
their superior archivers.

Co-authored-by: Dylan Baker <dylan@pnwbakers.com>

test cases/osx/9 global variable ar/libfile.c

@@ -0,0 +1,9 @@
+// Source: https://lists.gnu.org/archive/html/libtool/2002-07/msg00025.html
+
+#include <stdio.h>
+
+extern int l2;
+void l1(void)
+{
+  printf("l1 %d\n", l2);
+}

test cases/osx/9 global variable ar/libfile2.c

@@ -0,0 +1,7 @@
+// Source: https://lists.gnu.org/archive/html/libtool/2002-07/msg00025.html
+
+int l2;
+void l2_func(void)
+{
+  l2 = 77;
+}

test cases/osx/9 global variable ar/meson.build

@@ -0,0 +1,6 @@
+# Source: https://lists.gnu.org/archive/html/libtool/2002-07/msg00025.html
+
+project('global variable test', 'c')
+
+lib = static_library('mylib', 'libfile.c', 'libfile2.c')
+test('global variable', executable('prog', 'prog.c', link_with: lib))

test cases/osx/9 global variable ar/nativefile.ini

@@ -0,0 +1,2 @@
+[binaries]
+ar = 'ar'

test cases/osx/9 global variable ar/prog.c

@@ -0,0 +1,7 @@
+// Source: https://lists.gnu.org/archive/html/libtool/2002-07/msg00025.html
+
+extern void l1(void);
+int main(void)
+{
+  l1();
+}