build: pass include paths as a list instead of a string in cocoa check

when passed as a string check_cc tries to split that string, since it
assumes that several include paths can be passed to it. instead we just
use a list to make it unambiguous.

waftools/checks/custom.py

@@ -97,7 +97,7 @@ def check_cocoa(ctx, dependency_identifier):
         fragment         = load_fragment('cocoa.m'),
         compile_filename = 'test.m',
         framework_name   = ['Cocoa', 'IOKit', 'OpenGL', 'QuartzCore'],
-        includes         = ctx.srcnode.abspath(),
+        includes         = [ctx.srcnode.abspath()],
         linkflags        = '-fobjc-arc')
 
     res = fn(ctx, dependency_identifier)