Support the WITH_SHARED_TOOLCHAIN setting that was introduced in r234782

for the clang executable.  Build it statically by default, like the gcc
executables, which should improve performance a little bit.

MFC after:	1 week

usr.bin/clang/clang/Makefile

@@ -9,6 +9,10 @@ SRCS=	cc1_main.cpp \
 	cc1as_main.cpp \
 	driver.cpp
 
+.if ${MK_SHARED_TOOLCHAIN} == "no"
+NO_SHARED?= yes
+.endif
+
 LINKS=	${BINDIR}/clang ${BINDIR}/clang++ \
 	${BINDIR}/clang ${BINDIR}/clang-cpp
 MLINKS=	clang.1 clang++.1 \