Inline pg_ascii_tolower() and pg_ascii_toupper().

Discussion: https://postgr.es/m/450ceb6260cad30d7afdf155d991a9caafee7c0d.camel@j-davis.com
Reviewed-by: Chao Li <li.evan.chao@gmail.com>

src/include/port.h

@@ -169,8 +169,29 @@ extern int	pg_strcasecmp(const char *s1, const char *s2);
 extern int	pg_strncasecmp(const char *s1, const char *s2, size_t n);
 extern unsigned char pg_toupper(unsigned char ch);
 extern unsigned char pg_tolower(unsigned char ch);
-extern unsigned char pg_ascii_toupper(unsigned char ch);
-extern unsigned char pg_ascii_tolower(unsigned char ch);
+
+/*
+ * Fold a character to upper case, following C/POSIX locale rules.
+ */
+static inline unsigned char
+pg_ascii_toupper(unsigned char ch)
+{
+	if (ch >= 'a' && ch <= 'z')
+		ch += 'A' - 'a';
+	return ch;
+}
+
+/*
+ * Fold a character to lower case, following C/POSIX locale rules.
+ */
+static inline unsigned char
+pg_ascii_tolower(unsigned char ch)
+{
+	if (ch >= 'A' && ch <= 'Z')
+		ch += 'a' - 'A';
+	return ch;
+}
+
 
 /*
  * Beginning in v12, we always replace snprintf() and friends with our own

src/port/pgstrcasecmp.c

@@ -13,10 +13,6 @@
  *
  * NB: this code should match downcase_truncate_identifier() in scansup.c.
  *
- * We also provide strict ASCII-only case conversion functions, which can
- * be used to implement C/POSIX case folding semantics no matter what the
- * C library thinks the locale is.
- *
  *
  * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
  *
@@ -127,25 +123,3 @@ pg_tolower(unsigned char ch)
 		ch = tolower(ch);
 	return ch;
 }
-
-/*
- * Fold a character to upper case, following C/POSIX locale rules.
- */
-unsigned char
-pg_ascii_toupper(unsigned char ch)
-{
-	if (ch >= 'a' && ch <= 'z')
-		ch += 'A' - 'a';
-	return ch;
-}
-
-/*
- * Fold a character to lower case, following C/POSIX locale rules.
- */
-unsigned char
-pg_ascii_tolower(unsigned char ch)
-{
-	if (ch >= 'A' && ch <= 'Z')
-		ch += 'a' - 'A';
-	return ch;
-}