Disable new clang 10.0.0 warnings about misleading indentation in flex.

As this is contributed code with very messy indentation, which will
almost certainly never be upgraded, just disable the warning.

MFC after:	3 days

share/mk/bsd.sys.mk

@@ -111,6 +111,11 @@ CWARNFLAGS.clang+=	-Wno-parentheses
 .if defined(NO_WARRAY_BOUNDS)
 CWARNFLAGS.clang+=	-Wno-array-bounds
 .endif # NO_WARRAY_BOUNDS
+.if defined(NO_WMISLEADING_INDENTATION) && \
+    ((${COMPILER_TYPE} == "clang" && ${COMPILER_VERSION} >= 100000) || \
+     (${COMPILER_TYPE} == "gcc" && ${COMPILER_VERSION} >= 60100))
+CWARNFLAGS+=		-Wno-misleading-indentation
+.endif # NO_WMISLEADING_INDENTATION
 .endif # WARNS
 
 .if defined(FORMAT_AUDIT)
@@ -154,8 +159,7 @@ CWARNFLAGS+=	-Wno-error=address			\
 
 # GCC 6.1.0
 .if ${COMPILER_TYPE} == "gcc" && ${COMPILER_VERSION} >= 60100
-CWARNFLAGS+=	-Wno-error=misleading-indentation	\
-		-Wno-error=nonnull-compare		\
+CWARNFLAGS+=	-Wno-error=nonnull-compare		\
 		-Wno-error=shift-negative-value		\
 		-Wno-error=tautological-compare		\
 		-Wno-error=unused-const-variable

usr.bin/lex/Makefile

@@ -32,6 +32,8 @@ MLINKS+=	lex.1 lex++.1
 
 WARNS?=		3
 
+NO_WMISLEADING_INDENTATION=
+
 CLEANFILES=	scan.c skel.c
 GENFILES=	parse.c parse.h scan.c skel.c