i386: Switch to PIC kernel modules

It seems since the last llvm project update, the lld linker has started
creating a PLT dependent kernel module object files.

Reviewed by:		kib, jhb, emaste
Differential Revision:	https://reviews.freebsd.org/D41088

sys/conf/kmod.mk

@@ -166,7 +166,7 @@ CFLAGS+=	-fno-omit-frame-pointer -mno-omit-leaf-frame-pointer
 .endif
 
 .if ${MACHINE_CPUARCH} == "aarch64" || ${MACHINE_CPUARCH} == "riscv" || \
-    ${MACHINE_CPUARCH} == "powerpc"
+    ${MACHINE_CPUARCH} == "powerpc" || ${MACHINE_CPUARCH} == "i386"
 CFLAGS+=	-fPIC
 .endif
 

sys/i386/i386/elf_machdep.c

@@ -244,6 +244,7 @@ elf_reloc_internal(linker_file_t lf, Elf_Addr relocbase, const void *data,
 			break;
 
 		case R_386_GLOB_DAT:	/* S */
+		case R_386_JMP_SLOT:	/* S */
 			error = lookup(lf, symidx, 1, &addr);
 			if (error != 0)
 				return (-1);