Add profile for x86/i486

profiles/arch/x86/i486/make.defaults

+CHOST="i486-foxkit-linux-musl"
+
+# -O2           -> Perform second-level optimisations.
+#                  Not -Os because most/all x86 aren't starved for space.
+# -ggdb         -> Generate GDB debugging information.
+#                  This is used with splitdebug to make -dbg split packages.
+# -march=i486   -> Require an i486 or newer.
+# -mtune=pen... -> Tune for Pentium processors.
+CFLAGS="-O2 -ggdb -march=i486 -mtune=pentium"

profiles/arch/x86/i486/parent

+..