fix: move function declarations inside extern "C" block in number/float16/ctor

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---

Author: Planeshifter

lib/node_modules/@stdlib/number/float16/ctor/include/stdlib/number/float16/ctor.h

@@ -93,10 +93,6 @@ typedef union {
 
 #endif
 
-#ifdef __cplusplus
-}
-#endif
-
 /**
 * Converts a half-precision floating-point number to its binary representation.
 */
@@ -107,4 +103,8 @@ uint16_t stdlib_float16_to_bits( stdlib_float16_t x );
 */
 stdlib_float16_t stdlib_float16_from_bits( uint16_t bits );
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif // !STDLIB_NUMBER_FLOAT16_CTOR_H