Initial attempt to support the Solaris linker.

http://stackoverflow.com/a/16797248 suggests that libre2.symbols might
very well work as is.

Change-Id: I6cdf32cee25382c371ddac77c0a228019ffdb71e
Reviewed-on: https://code-review.googlesource.com/2771
Reviewed-by: Paul Wankadia <junyer@google.com>

Makefile

diff --git a/Makefile b/Makefile
index fd93441..801304d 100644
--- a/Makefile
+++ b/Makefile
@@ -39,8 +39,10 @@
 
 ifeq ($(shell uname),Darwin)
 MAKE_SHARED_LIBRARY=$(CXX) -dynamiclib $(LDFLAGS) -exported_symbols_list libre2.symbols.darwin
+else ifeq ($(shell uname),SunOS)
+MAKE_SHARED_LIBRARY=$(CXX) -shared -Wl,-soname,libre2.so.$(SONAME),-M,libre2.symbols $(LDFLAGS)
 else
-MAKE_SHARED_LIBRARY=$(CXX) -shared -Wl,-soname,libre2.so.$(SONAME),--version-script=libre2.symbols $(LDFLAGS)
+MAKE_SHARED_LIBRARY=$(CXX) -shared -Wl,-soname,libre2.so.$(SONAME),--version-script,libre2.symbols $(LDFLAGS)
 endif
 
 INSTALL_HFILES=\