Default configure builds shared libraries

Adding --enable-static now turnes off shared as it never build both at the same time

configure.ac

@@ -43,6 +43,23 @@ m4_ifdef([AM_SILENT_RULES], [AM_SILENT_RULES([yes])])
 ## ------------------------------ ##
 ## Hamlib specific configuration. ##
 ## ------------------------------ ##
+AC_ARG_ENABLE([shared],
+              [AS_HELP_STRING([--enable-shared],
+                              [Enable shared libraries @<:@default=yes@:>@])],
+              [enable_shared=$enableval],
+              [enable_shared=yes])
+AC_ARG_ENABLE([static],
+              [AS_HELP_STRING([--enable-static],
+                              [Enable static libraries @<:@default=check@:>@])],
+              [enable_static=$enableval],
+              [enable_static=check])
+
+AS_IF([test "x$enable_static" = "xyes"], [
+    enable_shared=no
+])
+AS_IF([test "x$enable_static" = "xyes" && test "x$enable_shared" = "xyes"], [
+    AC_MSG_ERROR([Both --enable-static and --enable-shared cannot be enabled at the same time.])
+])
 
 dnl New backends must be listed here!  Also the new Makefile path must be
 dnl added to AC_CONFIG_FILES near the end of this file.  See README.developer