Resolve redundant_static_lifetimes clippy lint from PR 2471

    error: constants have by default a `'static` lifetime
        --> serde/src/de/impls.rs:2467:24
         |
    2467 |     pub const FIELDS: &'static [&'static str] = &["end"];
         |                       -^^^^^^^--------------- help: consider removing `'static`: `&[&'static str]`
         |
         = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#redundant_static_lifetimes
         = note: `-D clippy::redundant-static-lifetimes` implied by `-D clippy::all`

    error: constants have by default a `'static` lifetime
        --> serde/src/de/impls.rs:2467:34
         |
    2467 |     pub const FIELDS: &'static [&'static str] = &["end"];
         |                                 -^^^^^^^---- help: consider removing `'static`: `&str`
         |
         = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#redundant_static_lifetimes

    error: constants have by default a `'static` lifetime
        --> serde/src/de/impls.rs:2605:24
         |
    2605 |     pub const FIELDS: &'static [&'static str] = &["start"];
         |                       -^^^^^^^--------------- help: consider removing `'static`: `&[&'static str]`
         |
         = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#redundant_static_lifetimes

    error: constants have by default a `'static` lifetime
        --> serde/src/de/impls.rs:2605:34
         |
    2605 |     pub const FIELDS: &'static [&'static str] = &["start"];
         |                                 -^^^^^^^---- help: consider removing `'static`: `&str`
         |
         = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#redundant_static_lifetimes

serde/src/de/impls.rs

@@ -1450,7 +1450,7 @@ macro_rules! variant_identifier {
             $($variant),*
         }
 
-        static $variants_name: &'static [&'static str] = &[$(stringify!($variant)),*];
+        static $variants_name: &[&str] = &[$(stringify!($variant)),*];
 
         impl<'de> Deserialize<'de> for $name_kind {
             fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
@@ -2464,7 +2464,7 @@ mod range_from {
 
     use de::{Deserialize, Deserializer, Error, MapAccess, SeqAccess, Visitor};
 
-    pub const FIELDS: &'static [&'static str] = &["end"];
+    pub const FIELDS: &[&str] = &["end"];
 
     // If this were outside of the serde crate, it would just use:
     //
@@ -2602,7 +2602,7 @@ mod range_to {
 
     use de::{Deserialize, Deserializer, Error, MapAccess, SeqAccess, Visitor};
 
-    pub const FIELDS: &'static [&'static str] = &["start"];
+    pub const FIELDS: &[&str] = &["start"];
 
     // If this were outside of the serde crate, it would just use:
     //