generalize references to exclusive builds

exclusive_builds_post.prf (via default_post.prf) processes
debug_and_release into BUILDS, so .prfs which can rely on being
executed later (because they are loaded via CONFIG) can rely on BUILDS
and related variables.

Change-Id: I5677079ad5145bf493af17b4b60347208572fd21
Reviewed-by: Jake Petroules <jake.petroules@qt.io>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>

mkspecs/features/file_copies.prf

@@ -1,8 +1,7 @@
 isEmpty(COPIES): return()
 contains(TEMPLATE, .*subdirs): error("COPIES does not work with TEMPLATE=subdirs")
 
-build_pass:build_all: \
-  debug_and_release:debug {
+build_pass:build_all:!isEqual(BUILD_PASS, $$first(BUILDS)) {
     # Avoid that multiple build passes race with each other.
     # This will fail to copy anything if the user explicitly invokes
     # only the non-primary build. This is unfixable, as at qmake time

mkspecs/features/qt_docs_targets.prf

@@ -30,7 +30,7 @@ contains(TEMPLATE, subdirs) {
     for(inst, DOC_TARGETS): \
         prepareRecursiveTarget($$inst)
 } else {
-    debug_and_release:!build_pass {
+    !isEmpty(BUILDS):!build_pass {
         sub = $$first(BUILDS)
         for(inst, DOC_TARGETS) {
             $${inst}.CONFIG = recursive

mkspecs/features/resources.prf

@@ -35,7 +35,7 @@ for(resource, RESOURCES) {
 
     resource_file = $$RCC_DIR/qmake_$${resource}.qrc
 
-    !debug_and_release|build_pass {
+    isEmpty(BUILDS)|build_pass {
         # Collection of files, generate qrc file
         prefix = $$eval($${resource}.prefix)
         isEmpty(prefix): \