meson: Add missing dependency to unicode test programs

The test programs in src/common/unicode/ (case_test, category_test,
norm_test), don't build with meson if the nls option is enabled,
because a libintl dependency is missing.  Fix that.  (The makefiles
are ok.)

Reviewed-by: Aleksander Alekseev <aleksander@timescale.com>
Discussion: https://www.postgresql.org/message-id/flat/52db1d2b-4b96-473e-b323-a4b16a950fba%40eisentraut.org

src/common/unicode/meson.build

@@ -104,7 +104,7 @@ inc = include_directories('.')
 
 case_test = executable('case_test',
   ['case_test.c'],
-  dependencies: [frontend_port_code, icu],
+  dependencies: [frontend_port_code, icu, libintl],
   include_directories: inc,
   link_with: [common_static, pgport_static],
   build_by_default: false,
@@ -115,7 +115,7 @@ case_test = executable('case_test',
 
 category_test = executable('category_test',
   ['category_test.c'],
-  dependencies: [frontend_port_code, icu],
+  dependencies: [frontend_port_code, icu, libintl],
   include_directories: inc,
   link_with: [common_static, pgport_static],
   build_by_default: false,
@@ -126,7 +126,7 @@ category_test = executable('category_test',
 
 norm_test = executable('norm_test',
   ['norm_test.c', norm_test_table],
-  dependencies: [frontend_port_code],
+  dependencies: [frontend_port_code, libintl],
   include_directories: inc,
   link_with: [common_static, pgport_static],
   build_by_default: false,