[build] Fix building on FreeBSD

FreeBSD requires the object format to be specified as elf_i386_fbsd,
rather than elf_i386.

Based on a patch from Eygene Ryabinkin <rea-fbsd@codelabs.ru>

src/Makefile.housekeeping

@@ -52,6 +52,14 @@ VERYCLEANUP	+= .echocheck
 echo :
 	@$(ECHO) "Using \"$(ECHO_E)\" for \"echo -e\""
 
+###############################################################################
+#
+# Determine host OS
+#
+HOST_OS		:= $(shell uname -s)
+hostos :
+	@$(ECHO) $(HOST_OS)
+
 ###############################################################################
 #
 # Check for tools that can cause failed builds

src/arch/i386/Makefile

@@ -38,8 +38,12 @@ CFLAGS		+= -freg-struct-return
 # Force 32-bit code even on an x86-64 machine
 #
 CFLAGS		+= -m32
-ASFLAGS         += --32
-LDFLAGS         += -m elf_i386
+ASFLAGS		+= --32
+ifeq ($(HOST_OS),FreeBSD)
+LDFLAGS		+= -m elf_i386_fbsd
+else
+LDFLAGS		+= -m elf_i386
+endif
 
 # EFI requires -fshort-wchar, and nothing else currently uses wchar_t
 #