Add strtoimax() compatibility function.

Since systems that omit strtoumax() will likely omit strtomax() too, and
likewise for strtoull() and strtoll(), we arrange for the make variables
NO_STRTOUMAX and NO_STRTOULL to cover both the signed and unsigned
functions, and define compatibility implementations for them.

Signed-off-by: Nick Alcock <nix@esperi.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Makefile

@@ -57,8 +57,8 @@ all::
 #
 # Define NO_STRLCPY if you don't have strlcpy.
 #
-# Define NO_STRTOUMAX if you don't have strtoumax in the C library.
-# If your compiler also does not support long long or does not have
+# Define NO_STRTOUMAX if you don't have both strtoimax and strtoumax in the
+# C library. If your compiler also does not support long long or does not have
 # strtoull, define NO_STRTOULL.
 #
 # Define NO_SETENV if you don't have setenv in the C library.
@@ -1402,7 +1402,7 @@ ifdef NO_STRLCPY
 endif
 ifdef NO_STRTOUMAX
 	COMPAT_CFLAGS += -DNO_STRTOUMAX
-	COMPAT_OBJS += compat/strtoumax.o
+	COMPAT_OBJS += compat/strtoumax.o compat/strtoimax.o
 endif
 ifdef NO_STRTOULL
 	COMPAT_CFLAGS += -DNO_STRTOULL

compat/strtoimax.c

@@ -0,0 +1,10 @@
+#include "../git-compat-util.h"
+
+intmax_t gitstrtoimax (const char *nptr, char **endptr, int base)
+{
+#if defined(NO_STRTOULL)
+	return strtol(nptr, endptr, base);
+#else
+	return strtoll(nptr, endptr, base);
+#endif
+}