stack: fix stubs header export

[ upstream commit 8adf5f528bf3321feeae2231007ebae162032739 ]

The stubs header is included as part of rte_stack.h for architectures
other than x86_64 and aarch64 (i.e. x86 32 bits and ppc).

Note: chkincs won't catch this issue since it checks headers from within
the source directory.

Fixes: 7911ba0 ("stack: enable lock-free implementation for aarch64")

Signed-off-by: David Marchand <david.marchand@redhat.com>

lib/librte_stack/meson.build

@@ -8,4 +8,6 @@ headers = files('rte_stack.h',
 		'rte_stack_std.h',
 		'rte_stack_lf.h',
 		'rte_stack_lf_generic.h',
-		'rte_stack_lf_c11.h')
+		'rte_stack_lf_c11.h',
+		'rte_stack_lf_stubs.h',
+)