apr: build some needed emulated 64-bit atomic bits after r361678

This should fix the build on armv{6,7}, mips, and mips64, which all need
emulated 64-bit atomics for apr.

X-MFC-With:	r361678

usr.bin/svn/lib/libapr/Makefile

@@ -19,6 +19,7 @@ SRCS=		apr_cpystrn.c \
 		apr_tables.c \
 		buffer.c \
 		builtins.c \
+		builtins64.c \
 		charset.c \
 		common.c \
 		copy.c \
@@ -45,6 +46,7 @@ SRCS=		apr_cpystrn.c \
 		mmap.c \
 		multicast.c \
 		mutex.c \
+		mutex64.c \
 		open.c \
 		otherchild.c \
 		pipe.c \