Eliminate doRmSource() from librpmbuild API again

- buildSpec() is sufficient interface for accomplishing the same,
  avoid exposing internal helpers

build/build.c

@@ -18,7 +18,7 @@ static int _build_debug = 0;
 
 /**
  */
-rpmRC doRmSource(rpmSpec spec)
+static rpmRC doRmSource(rpmSpec spec)
 {
     struct Source *p;
     Package pkg;

build/rpmbuild.h

@@ -252,13 +252,6 @@ int parseScript(rpmSpec spec, int parsePart);
  */
 int parseExpressionBoolean(rpmSpec spec, const char * expr);
 
-/** \ingroup rpmbuild
- * Remove all sources assigned to spec file.
- *
- * @param spec		spec file control structure
- * @return		RPMRC_OK on success
- */
-rpmRC doRmSource(rpmSpec spec);
 /** \ingroup rpmbuild
  * Run a build script, assembled from spec file scriptlet section.
  *