[WIP] add support for minimum supported rust version

fixes rust-lang#6097

Author: suyashb95

clippy_lints/src/manual_non_exhaustive.rs

@@ -7,6 +7,8 @@ use rustc_lint::{EarlyContext, EarlyLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::Span;
 
+const MSRV: &str = "1.40";
+
 declare_clippy_lint! {
     /// **What it does:** Checks for manual implementations of the non-exhaustive pattern.
     ///

clippy_lints/src/manual_strip.rs

@@ -17,6 +17,8 @@ use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::source_map::Spanned;
 use rustc_span::Span;
 
+const MSRV: &str = "1.45";
+
 declare_clippy_lint! {
     /// **What it does:**
     /// Suggests using `strip_{prefix,suffix}` over `str::{starts,ends}_with` and slicing using