Fix build with new binutils. This gets a working kernel with GCC 5.2 and

binutils 2.24. Without this, the self-relocation code in locore64.S was
failing due to a misaligned TOC section.

MFC after:	2 weeks

sys/conf/ldscript.powerpc64

@@ -69,6 +69,7 @@ SECTIONS
   .toc1      : ALIGN(8) { *(.toc1) }
   .opd       : ALIGN(8) { KEEP (*(.opd)) }
   .branch_lt : ALIGN(8) { *(.branch_lt) }
+  . = ALIGN(4096);
   .got       : ALIGN(8) { __tocbase = .; *(.got .toc) }
 
   .dynamic        : { *(.dynamic) }