build: move from c++11 to c++17

Moving from cpp 11 to cpp 17 will allow us to use modern features like
filesystem support, optional, any, execution policies and improved
templates.

Signed-off-by: Nathan Gauër <brioche@google.com>

CMakeLists.txt

@@ -196,7 +196,7 @@ function(spvtools_default_compile_options TARGET)
   target_compile_options(${TARGET} PRIVATE ${SPIRV_WARNINGS})
 
   if (${COMPILER_IS_LIKE_GNU})
-    target_compile_options(${TARGET} PRIVATE -std=c++11 -fno-exceptions)
+    target_compile_options(${TARGET} PRIVATE -std=c++17 -fno-exceptions)
     target_compile_options(${TARGET} PRIVATE
       -Wall -Wextra -Wno-long-long -Wshadow -Wundef -Wconversion
       -Wno-sign-conversion)