skslc now uses a more recent version of Flex

Bug: 6447
Change-Id: Ie1cb674752442a8992dd247abb2bcace8497c1f4
Reviewed-on: https://skia-review.googlesource.com/11014
Reviewed-by: Ben Wagner <benjaminwagner@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>

src/sksl/SkSLParser.cpp

@@ -12,6 +12,9 @@
 #define register
 #include "disable_flex_warnings.h"
 #include "lex.sksl.c"
+static_assert(YY_FLEX_MAJOR_VERSION * 100 + YY_FLEX_MINOR_VERSION * 10 +
+              YY_FLEX_SUBMINOR_VERSION >= 261,
+              "we require Flex 2.6.1 or better for security reasons");
 #undef register
 #ifdef __clang__
 #pragma clang diagnostic pop

src/sksl/lex.layout.cpp

@@ -7,3 +7,6 @@
 
 #include "disable_flex_warnings.h"
 #include "lex.layout.c"
+static_assert(YY_FLEX_MAJOR_VERSION * 100 + YY_FLEX_MINOR_VERSION * 10 +
+              YY_FLEX_SUBMINOR_VERSION >= 261,
+              "we require Flex 2.6.1 or better for security reasons");