Remove -Os compiler flag.

Hardcoding it in that fashion interferes with the default Meson
debug build type. We still need to figure out how to force that for
the optimized build type but that can be punted far down the road.

meson.build

@@ -5,10 +5,6 @@ project('ksh93', 'c', default_options: ['b_lundef=false', 'default_library=stati
 # does that but also limits which APIs are available.
 add_global_arguments('-std=gnu99', language: 'c')
 
-# Compiling for small code size is usually the better choice unless
-# benchmarking shows otherwise.
-add_global_arguments('-Os', language: 'c')
-
 # Without this flag some symbols aren't visible.
 #
 # TODO: Figure out if there is a more generic manner of enabling support for