Older distros don't have it, but newer distros do. Normally this would be
handled by autoconf, but that's unnecessarily complicated to integrate
into the bazel build, and fortunately it's only used by xasprintf.

diff --git a/src/common.c b/src/common.c
index aa3a02b..9ab7f09 100644
--- a/src/common.c
+++ b/src/common.c
@@ -117,8 +117,7 @@ int min(int a, int b)
 }
 
 
-#ifndef HAVE_VASPRINTF
-static int vasprintf(char **strp, const char *fmt, va_list va)
+static int dosfstools_vasprintf(char **strp, const char *fmt, va_list va)
 {
     int length;
     va_list vacopy;
@@ -137,7 +136,6 @@ static int vasprintf(char **strp, const char *fmt, va_list va)
 
     return vsnprintf(*strp, length + 1, fmt, va);
 }
-#endif
 
 int xasprintf(char **strp, const char *fmt, ...)
 {
@@ -145,7 +143,7 @@ int xasprintf(char **strp, const char *fmt, ...)
     int retval;
 
     va_start(va, fmt);
-    retval = vasprintf(strp, fmt, va);
+    retval = dosfstools_vasprintf(strp, fmt, va);
     va_end(va);
 
     if (retval < 0)