tests: add test to ensure that build dir is preferred to src dir

Extend the "common/include order" test to ensure that the build
directory is preferred over the source directory. For example,
when using `configure_file()`, the resulting file should be
preferred over a file with the same name in the source directory.

test cases/common/130 include order/inc3/meson.build

@@ -0,0 +1,2 @@
+configure_file(output: 'prefer-build-dir-over-src-dir.h',
+               configuration: configuration_data())

test cases/common/130 include order/inc3/prefer-build-dir-over-src-dir.h

@@ -0,0 +1 @@
+#error "inc3/prefer-build-dir-over-src-dir.h included"

test cases/common/130 include order/meson.build

@@ -12,6 +12,8 @@ project('include order', 'c')
 
 # Custom target dir with a built header
 subdir('ctsub')
+# Configures a header file
+subdir('inc3')
 # Defines an internal dep
 subdir('sub1')
 # Defines a per-target include path
@@ -32,5 +34,5 @@ test('eh', e)
 test('oh', f)
 
 # Test that the order in include_directories() is maintained
-incs = include_directories('inc1', 'inc2')
+incs = include_directories('inc1', 'inc2', 'inc3')
 executable('ordertest', 'ordertest.c', include_directories: incs)

test cases/common/130 include order/ordertest.c

@@ -1,4 +1,5 @@
 #include "hdr.h"
+#include "prefer-build-dir-over-src-dir.h"
 
 #if !defined(SOME_DEFINE) || SOME_DEFINE != 42
 #error "Should have picked up hdr.h from inc1/hdr.h"