loader: --gc-sections needs sections to work with

--gc-sections is not really useful unless we generate sections with
-ffunction-sections -fdata-sections

While there, i386/loader would win from --gc-sections too.

stand/defs.mk

@@ -65,6 +65,7 @@ CFLAGS+=	-Ddouble=jagged-little-pill -Dfloat=floaty-mcfloatface
 # Experience has shown that problems arise between ~520k to ~530k.
 CFLAGS.clang+=	-Oz
 CFLAGS.gcc+=	-Os
+CFLAGS+=	-ffunction-sections -fdata-sections
 .endif
 
 # GELI Support, with backward compat hooks (mostly)

stand/i386/loader/Makefile

@@ -47,7 +47,7 @@ HELP_FILES=	${.CURDIR}/help.i386
 CLEANFILES+=	${LOADER} ${LOADER}.bin
 
 CFLAGS+=	-Wall
-LDFLAGS+=	-static -Ttext 0x0
+LDFLAGS+=	-static -Ttext 0x0 -Wl,--gc-sections
 
 # i386 standalone support library
 LIBI386=	${BOOTOBJ}/i386/libi386/libi386.a