Add support for AmigaOS/AROS to tuklib_physmem().

Thanks to Fredrik Wikstrom.

m4/tuklib_physmem.m4

@@ -53,7 +53,8 @@ AC_CACHE_CHECK([how to detect the amount of physical memory],
 # a non-compilable text instead of #error to generate an error.
 AC_COMPILE_IFELSE([AC_LANG_SOURCE([[
 #if defined(_WIN32) || defined(__CYGWIN__) || defined(__OS2__) \
-		|| defined(__DJGPP__) || defined(__VMS)
+		|| defined(__DJGPP__) || defined(__VMS) \
+		|| defined(AMIGA) || defined(__AROS__)
 int main(void) { return 0; }
 #else
 compile error

src/common/tuklib_physmem.c

@@ -33,6 +33,10 @@
 #	include <syidef.h>
 #	include <ssdef.h>
 
+#elif defined(AMIGA) || defined(__AROS__)
+#	define __USE_INLINE__
+#	include <proto/exec.h>
+
 // AIX
 #elif defined(TUKLIB_PHYSMEM_AIX)
 #	include <sys/systemcfg.h>
@@ -119,6 +123,9 @@ tuklib_physmem(void)
 	if (LIB$GETSYI(&val, &vms_mem, 0, 0, 0, 0) == SS$_NORMAL)
 		ret = (uint64_t)vms_mem * 8192;
 
+#elif defined(AMIGA) || defined(__AROS__)
+	ret = AvailMem(MEMF_TOTAL);
+
 #elif defined(TUKLIB_PHYSMEM_AIX)
 	ret = _system_configuration.physmem;