build: Always enable -Wmisleading-indentation

Try and ensure that people don’t push code with misleading indentation
in future. This should give fairly few false positives.

Signed-off-by: Philip Withnall <withnall@endlessm.com>

configure.ac

@@ -3508,7 +3508,7 @@ AC_ARG_ENABLE(compile-warnings,
 			      enable_compile_warnings=yes)
 AS_IF([test "x$enable_compile_warnings" != xno], [
   CC_CHECK_FLAGS_APPEND([GLIB_WARN_CFLAGS], [CFLAGS], [\
-   -Wall -Wstrict-prototypes -Wduplicated-branches \
+   -Wall -Wstrict-prototypes -Wduplicated-branches -Wmisleading-indentation \
    -Werror=declaration-after-statement \
    -Werror=missing-prototypes -Werror=implicit-function-declaration \
    -Werror=pointer-arith -Werror=init-self -Werror=format-security \

meson.build

@@ -331,6 +331,7 @@ if cc.get_id() == 'gcc' or cc.get_id() == 'clang'
   test_c_args = [
     '-Wall',
     '-Wduplicated-branches',
+    '-Wmisleading-indentation',
     '-Wstrict-prototypes',
     '-Wunused',
     '-Werror=declaration-after-statement',