add missing startfiles for powerpc

crt/powerpc/crti.s

@@ -0,0 +1,15 @@
+.section .init
+.align 2
+.global _init
+_init:
+	stwu 1,-32(1)
+	mflr 0
+	stw 0,36(1)
+
+.section .fini
+.align 2
+.global _fini
+_fini:
+	stwu 1,-32(1)
+	mflr 0
+	stw 0,36(1)

crt/powerpc/crtn.s

@@ -0,0 +1,13 @@
+.section .init
+.align 2
+	lwz 0,36(1)
+	addi 1,1,32
+	mtlr 0
+	blr
+
+.section .fini
+.align 2
+	lwz 0,36(1)
+	addi 1,1,32
+	mtlr 0
+	blr