Simplify non-wrapping += and *=

Use this replacement file as described in other recent PRs to replace boilerplate code.

<details>
<summary>replacement file content</summary>

```diff
@@
expression expr_r, expr_l;
@@
-{
-   let _rhs = expr_r;
-   let _lhs = &mut expr_l;
-   *_lhs *= _rhs;
+expr_l *= expr_r;
-}

@@
expression expr_r, expr_l;
@@
-{
-   let _rhs = expr_r;
-   let _lhs = &mut expr_l;
-   *_lhs += _rhs;
+expr_l += expr_r;
-}
```

</details>

Author: nyurik

src/enc/encode.rs

@@ -1819,37 +1819,21 @@ fn ChooseContextMap(
     entropy[3] = 0i32 as (super::util::floatX);
     i = 0usize;
     while i < 3usize {
-        {
-            let _rhs = ShannonEntropy(
-                &bigram_histo[(3usize).wrapping_mul(i)..],
-                3usize,
-                &mut dummy,
-            );
-            let _lhs = &mut entropy[3];
-            *_lhs += _rhs;
-        }
+        entropy[3] += ShannonEntropy(
+            &bigram_histo[(3usize).wrapping_mul(i)..],
+            3usize,
+            &mut dummy,
+        );
         i = i.wrapping_add(1);
     }
     let total: usize = monogram_histo[0]
         .wrapping_add(monogram_histo[1])
         .wrapping_add(monogram_histo[2]) as usize;
     0i32;
     entropy[0] = 1.0 as super::util::floatX / total as (super::util::floatX);
-    {
-        let _rhs = entropy[0];
-        let _lhs = &mut entropy[1];
-        *_lhs *= _rhs;
-    }
-    {
-        let _rhs = entropy[0];
-        let _lhs = &mut entropy[2];
-        *_lhs *= _rhs;
-    }
-    {
-        let _rhs = entropy[0];
-        let _lhs = &mut entropy[3];
-        *_lhs *= _rhs;
-    }
+    entropy[1] *= entropy[0];
+    entropy[2] *= entropy[0];
+    entropy[3] *= entropy[0];
     if quality < 7i32 {
         entropy[3] = entropy[1] * 10i32 as (super::util::floatX);
     }

src/enc/metablock.rs

@@ -732,11 +732,7 @@ fn ContextBlockSplitterFinishBlock<
                         );
                         combined_entropy[jx] =
                             BitsEntropy(combined_histo.slice()[jx].slice(), xself.alphabet_size_);
-                        {
-                            let _rhs = combined_entropy[jx] - entropy[i] - xself.last_entropy_[jx];
-                            let _lhs = &mut diff[j];
-                            *_lhs += _rhs;
-                        }
+                        diff[j] += combined_entropy[jx] - entropy[i] - xself.last_entropy_[jx];
                     }
                     j = j.wrapping_add(1);
                 }

src/enc/test.rs

@@ -58,9 +58,11 @@ fn oneshot_compress(
         unsafe { define_allocator_memory_pool!(96, u64, [0; 32 * 1024], calloc) };
     let stack_f64_buffer =
         unsafe { define_allocator_memory_pool!(48, super::util::floatX, [0; 128 * 1024], calloc) };
-    let mut stack_global_buffer_v8 = define_allocator_memory_pool!(64, v8, [v8::default(); 1024 * 16], stack);
+    let mut stack_global_buffer_v8 =
+        define_allocator_memory_pool!(64, v8, [v8::default(); 1024 * 16], stack);
     let mf8 = StackAllocatedFreelist64::<v8>::new_allocator(&mut stack_global_buffer_v8, bzero);
-    let mut stack_16x16_buffer = define_allocator_memory_pool!(64, s16, [s16::default(); 1024 * 16], stack);
+    let mut stack_16x16_buffer =
+        define_allocator_memory_pool!(64, s16, [s16::default(); 1024 * 16], stack);
     let m16x16 = StackAllocatedFreelist64::<s16>::new_allocator(&mut stack_16x16_buffer, bzero);
 
     let stack_hl_buffer =

src/enc/vectorization.rs

@@ -1,10 +1,10 @@
 #![allow(unknown_lints)]
 #![allow(unused_macros)]
 
-use enc::util::FastLog2;
-use enc::{s8, v8};
 #[cfg(feature = "simd")]
 use core::simd::Simd;
+use enc::util::FastLog2;
+use enc::{s8, v8};
 pub type Mem256f = v8;
 pub type Mem256i = s8;
 pub type v256 = v8;