meson: Apply `b_ndebug=if-release` by default

Disable assertions in release builds by default. In addition to
improving the safety of the library, with GCC 13.1.1 on aarch64 (Fedora
38) this reduces the text section by slightly more than 4KiB:

```
$ size build.undebug/libpldm.so build.ndebug/libpldm.so
   text    data     bss     dec     hex filename
 109827    1448      16  111291   1b2bb build.undebug/libpldm.so
 105395    1440      16  106851   1a163 build.ndebug/libpldm.so
$ echo $((109827 - 105395))
4432
```

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Change-Id: I59d9bf2c636284c649abbdcc14a3c350d9ca94fd
diff --git a/meson.build b/meson.build
index da594cb..ad5cd8d 100644
--- a/meson.build
+++ b/meson.build
@@ -6,6 +6,7 @@
       'werror=true',
       'cpp_std=c++20',
       'c_std=c17',
+      'b_ndebug=if-release',
       'tests=' + (meson.is_subproject() ? 'disabled' : 'enabled'),
     ],
     version: '0.5.0',