On Solaris, link shared libraries with --shared rather than -G.

ChangeLog

+2020-02-05  Niels Möller  <nisse@lysator.liu.se>
+
+	* configure.ac: On Solaris, link shared libraries with --shared
+	rather than -G. For gcc, --shared is the proper way. For Solaris'
+	proprietary cc, according to docs, it accepts --shared as an alias
+	for -G since Oracle Solaris Studio 12.4, and it was made more gcc
+	compatible in later versions. Since 12.4 was released in 2014,
+	don't attempt to cater for older versions.
+
 2020-01-26  Niels Möller  <nisse@lysator.liu.se>
 
 	* ecc-internal.h (struct ecc_curve): Delete g, the curve

configure.ac

@@ -655,13 +655,13 @@ case "$host_os" in
     LIBNETTLE_FORLINK=libnettle.so
     LIBNETTLE_SONAME='$(LIBNETTLE_FORLINK).$(LIBNETTLE_MAJOR)'
     LIBNETTLE_FILE='$(LIBNETTLE_SONAME).$(LIBNETTLE_MINOR)'
-    LIBNETTLE_LINK='$(CC) $(CFLAGS) $(LDFLAGS) -G -h $(LIBNETTLE_SONAME)'
+    LIBNETTLE_LINK='$(CC) $(CFLAGS) $(LDFLAGS) -shared -h $(LIBNETTLE_SONAME)'
     LIBNETTLE_LIBS=''
 
     LIBHOGWEED_FORLINK=libhogweed.so
     LIBHOGWEED_SONAME='$(LIBHOGWEED_FORLINK).$(LIBHOGWEED_MAJOR)'
     LIBHOGWEED_FILE='$(LIBHOGWEED_SONAME).$(LIBHOGWEED_MINOR)'
-    LIBHOGWEED_LINK='$(CC) $(CFLAGS) $(LDFLAGS) -G -h $(LIBHOGWEED_SONAME)'
+    LIBHOGWEED_LINK='$(CC) $(CFLAGS) $(LDFLAGS) --shared -h $(LIBHOGWEED_SONAME)'
     LIBHOGWEED_LIBS='libnettle.so $(LIBS)'
     ;;
   *)