compat: add strtok_r()

Windows does not have strtok_r (and while it does have an identical
strtok_s, but it is not obvious how to use it).  Grab an
implementation from glibc.

The svn-fe tool uses strtok_r to parse paths.

Acked-by: Johannes Sixt <j6t@kdbg.org>
Helped-by: Jakub Narebski <jnareb@gmail.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/Makefile b/Makefile
index 3452700..fbc6581 100644
--- a/Makefile
+++ b/Makefile
@@ -68,6 +68,8 @@
 #
 # Define NO_MKSTEMPS if you don't have mkstemps in the C library.
 #
+# Define NO_STRTOK_R if you don't have strtok_r in the C library.
+#
 # Define NO_LIBGEN_H if you don't have libgen.h.
 #
 # Define NEEDS_LIBGEN if your libgen needs -lgen when linking
@@ -1041,6 +1043,7 @@
 	NO_UNSETENV = YesPlease
 	NO_STRCASESTR = YesPlease
 	NO_STRLCPY = YesPlease
+	NO_STRTOK_R = YesPlease
 	NO_MEMMEM = YesPlease
 	# NEEDS_LIBICONV = YesPlease
 	NO_ICONV = YesPlease
@@ -1095,6 +1098,7 @@
 	NO_UNSETENV = YesPlease
 	NO_STRCASESTR = YesPlease
 	NO_STRLCPY = YesPlease
+	NO_STRTOK_R = YesPlease
 	NO_MEMMEM = YesPlease
 	NEEDS_LIBICONV = YesPlease
 	OLD_ICONV = YesPlease
@@ -1325,6 +1329,10 @@
 ifdef NO_STRTOULL
 	COMPAT_CFLAGS += -DNO_STRTOULL
 endif
+ifdef NO_STRTOK_R
+	COMPAT_CFLAGS += -DNO_STRTOK_R
+	COMPAT_OBJS += compat/strtok_r.o
+endif
 ifdef NO_SETENV
 	COMPAT_CFLAGS += -DNO_SETENV
 	COMPAT_OBJS += compat/setenv.o