meson.build: drop -Wno-error=strict-aliasing

This was added in error (88873e295b) but
we discussed it in !2180 and it turned out CFLAGS="... -fstrict-aliasing"
was set in the environment, overriding the earlier -fno-strict-aliasing
already set in meson.build (which we're keeping here).

That is, when -fno-strict-aliasing is in-effect, there's already no
need for -Wno-error=strict-aliasing (as the warnings aren't emitted), but
if there *is* a need for a -Wno-error=strict-aliasing for a user, it
means they're (likely unintentionally) enabling strict-aliasing and we
certainly want to make them aware of that.

meson.build

@@ -81,7 +81,6 @@ pkgconfig = import('pkgconfig')
 common_flags = [
   '-fvisibility=hidden',
   '-fno-strict-aliasing',
-  '-Wno-error=strict-aliasing',
   '-Werror=suggest-attribute=format',
   '-Wsign-compare',
   '-Wpointer-arith',