Add support for Solaris / Illumos.
diff --git a/absl/base/config.h b/absl/base/config.h
index 2f5f159..6890e31 100644
--- a/absl/base/config.h
+++ b/absl/base/config.h
@@ -268,7 +268,7 @@
 #error ABSL_HAVE_MMAP cannot be directly set
 #elif defined(__linux__) || defined(__APPLE__) || defined(__FreeBSD__) ||   \
     defined(__ros__) || defined(__native_client__) || defined(__asmjs__) || \
-    defined(__wasm__) || defined(__Fuchsia__)
+    defined(__wasm__) || defined(__Fuchsia__) || defined(__sun)
 #define ABSL_HAVE_MMAP 1
 #endif