Simplify strchrnul() compat code

strchrnul() was introduced in glibc in April 1999 and included in
glibc-2.1. Checking for that version means the majority of all git
users would get to use the optimized version in glibc. Of the
remaining few some might get to use a slightly slower version
than necessary but probably not slower than what we have today.

Unfortunately, __GLIBC_PREREQ() macro was not available in glibc 2.1.1
which was short lived but already supported strchrnul().  Odd minority
users of that library needs to live with our compatibility inline version.

Rediffed-against-next-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Makefile

@@ -30,8 +30,6 @@ all::
 #
 # Define NO_MEMMEM if you don't have memmem.
 #
-# Define NO_STRCHRNUL if you don't have strchrnul.
-#
 # Define NO_STRLCPY if you don't have strlcpy.
 #
 # Define NO_STRTOUMAX if you don't have strtoumax in the C library.
@@ -408,7 +406,6 @@ ifeq ($(uname_S),Darwin)
 	OLD_ICONV = UnfortunatelyYes
 	NO_STRLCPY = YesPlease
 	NO_MEMMEM = YesPlease
-	NO_STRCHRNUL = YesPlease
 endif
 ifeq ($(uname_S),SunOS)
 	NEEDS_SOCKET = YesPlease
@@ -416,7 +413,6 @@ ifeq ($(uname_S),SunOS)
 	SHELL_PATH = /bin/bash
 	NO_STRCASESTR = YesPlease
 	NO_MEMMEM = YesPlease
-	NO_STRCHRNUL = YesPlease
 	NO_HSTRERROR = YesPlease
 	ifeq ($(uname_R),5.8)
 		NEEDS_LIBICONV = YesPlease
@@ -442,7 +438,6 @@ ifeq ($(uname_O),Cygwin)
 	NO_D_INO_IN_DIRENT = YesPlease
 	NO_STRCASESTR = YesPlease
 	NO_MEMMEM = YesPlease
-	NO_STRCHRNUL = YesPlease
 	NO_SYMLINK_HEAD = YesPlease
 	NEEDS_LIBICONV = YesPlease
 	NO_FAST_WORKING_DIRECTORY = UnfortunatelyYes
@@ -457,14 +452,12 @@ endif
 ifeq ($(uname_S),FreeBSD)
 	NEEDS_LIBICONV = YesPlease
 	NO_MEMMEM = YesPlease
-	NO_STRCHRNUL = YesPlease
 	BASIC_CFLAGS += -I/usr/local/include
 	BASIC_LDFLAGS += -L/usr/local/lib
 endif
 ifeq ($(uname_S),OpenBSD)
 	NO_STRCASESTR = YesPlease
 	NO_MEMMEM = YesPlease
-	NO_STRCHRNUL = YesPlease
 	NEEDS_LIBICONV = YesPlease
 	BASIC_CFLAGS += -I/usr/local/include
 	BASIC_LDFLAGS += -L/usr/local/lib
@@ -480,7 +473,6 @@ endif
 ifeq ($(uname_S),AIX)
 	NO_STRCASESTR=YesPlease
 	NO_MEMMEM = YesPlease
-	NO_STRCHRNUL = YesPlease
 	NO_STRLCPY = YesPlease
 	NEEDS_LIBICONV=YesPlease
 endif
@@ -493,7 +485,6 @@ ifeq ($(uname_S),IRIX64)
 	NO_SETENV=YesPlease
 	NO_STRCASESTR=YesPlease
 	NO_MEMMEM = YesPlease
-	NO_STRCHRNUL = YesPlease
 	NO_STRLCPY = YesPlease
 	NO_SOCKADDR_STORAGE=YesPlease
 	SHELL_PATH=/usr/gnu/bin/bash
@@ -704,10 +695,6 @@ ifdef NO_MEMMEM
 	COMPAT_CFLAGS += -DNO_MEMMEM
 	COMPAT_OBJS += compat/memmem.o
 endif
-ifdef NO_STRCHRNUL
-	COMPAT_CFLAGS += -DNO_STRCHRNUL
-	COMPAT_OBJS += compat/strchrnul.o
-endif
 
 ifdef THREADED_DELTA_SEARCH
 	BASIC_CFLAGS += -DTHREADED_DELTA_SEARCH

compat/strchrnul.c

@@ -1,8 +0,0 @@
-#include "../git-compat-util.h"
-
-char *gitstrchrnul(const char *s, int c)
-{
-	while (*s && *s != c)
-		s++;
-	return (char *)s;
-}

git-compat-util.h

@@ -183,9 +183,14 @@ void *gitmemmem(const void *haystack, size_t haystacklen,
                 const void *needle, size_t needlelen);
 #endif
 
-#ifdef NO_STRCHRNUL
+#if !defined(__GLIBC_PREREQ) && !__GLIBC_PREREQ(2, 1)
 #define strchrnul gitstrchrnul
-char *gitstrchrnul(const char *s, int c);
+static inline char *gitstrchrnul(const char *s, int c)
+{
+	while (*s && *s != c)
+		s++;
+	return (char *)s;
+}
 #endif
 
 extern void release_pack_memory(size_t, int);