parser.c: Always inline json_eat_whitespace

```
== Parsing activitypub.json (58160 bytes)
ruby 3.4.6 (2025-09-16 revision dbd83256b1) +YJIT +PRISM [arm64-darwin24]
Warming up --------------------------------------
               after     1.174k i/100ms
Calculating -------------------------------------
               after     11.756k (± 0.9%) i/s   (85.06 μs/i) -     59.874k in   5.093438s

Comparison:
              before:    11078.6 i/s
               after:    11756.1 i/s - 1.06x  faster

== Parsing twitter.json (567916 bytes)
ruby 3.4.6 (2025-09-16 revision dbd83256b1) +YJIT +PRISM [arm64-darwin24]
Warming up --------------------------------------
               after   130.000 i/100ms
Calculating -------------------------------------
               after      1.340k (± 0.3%) i/s  (746.06 μs/i) -      6.760k in   5.043432s

Comparison:
              before:     1191.1 i/s
               after:     1340.4 i/s - 1.13x  faster

== Parsing citm_catalog.json (1727030 bytes)
ruby 3.4.6 (2025-09-16 revision dbd83256b1) +YJIT +PRISM [arm64-darwin24]
Warming up --------------------------------------
               after    68.000 i/100ms
Calculating -------------------------------------
               after    689.451 (± 1.6%) i/s    (1.45 ms/i) -      3.468k in   5.031470s

Comparison:
              before:      630.3 i/s
               after:      689.5 i/s - 1.09x  faster

== Parsing float parsing (2251051 bytes)
ruby 3.4.6 (2025-09-16 revision dbd83256b1) +YJIT +PRISM [arm64-darwin24]
Warming up --------------------------------------
               after    27.000 i/100ms
Calculating -------------------------------------
               after    248.265 (± 0.8%) i/s    (4.03 ms/i) -      1.242k in   5.003185s

Comparison:
              before:      232.7 i/s
               after:      248.3 i/s - 1.07x  faster
```

Co-Authored-By: Scott Myron <[email protected]>

Author: byroot

ext/json/ext/parser/parser.c

@@ -513,7 +513,7 @@ json_eat_comments(JSON_ParserState *state)
     }
 }
 
-static inline void
+static ALWAYS_INLINE() void
 json_eat_whitespace(JSON_ParserState *state)
 {
     while (true) {