loader: Make pkcs5v2 unconditionally available

This was previously only available if GELI support was included, but I
want to use it for processing entropy from EFI

Reviewed by:	imp
MFC after:	1 week
Sponsored by:	Amazon
Differential Revision:	https://reviews.freebsd.org/D46634

stand/libsa/Makefile

@@ -164,6 +164,10 @@ CFLAGS.bzipfs.c+= -I${SRCTOP}/contrib/bzip2  -DBZ_NO_STDIO -DBZ_NO_COMPRESS
 .PATH: ${SYSDIR}/libkern
 SRCS+=  explicit_bzero.c crc32_libkern.c
 
+# Bits from GELI which are reused elsewhere
+.PATH: ${SYSDIR}/geom/eli
+SRCS+=	g_eli_hmac.c pkcs5v2.c
+
 # Maybe GELI
 .if ${MK_LOADER_GELI} == "yes"
 .include "${SASRC}/geli/Makefile.inc"

stand/libsa/geli/Makefile.inc

@@ -21,10 +21,8 @@ SRCS+=		${i}
 .endfor
 SRCS+=		geliboot.c \
 		geliboot_crypto.c \
-		g_eli_hmac.c \
 		g_eli_key.c \
 		g_eli_key_cache.c \
-		pkcs5v2.c \
 
 # aes
 .PATH:		${SYSDIR}/opencrypto