Add test for prev/back arrows + examples across multiple files

src/test/run-make/rustdoc-scrape-examples-multiple/Makefile

@@ -0,0 +1,21 @@
+-include ../../run-make-fulldeps/tools.mk
+
+OUTPUT_DIR := "$(TMPDIR)/rustdoc"
+
+all: $(TMPDIR)/ex.calls $(TMPDIR)/ex2.calls
+	$(RUSTDOC) src/lib.rs --crate-name foobar --crate-type lib --output $(OUTPUT_DIR) \
+		-Z unstable-options \
+		--with-examples $(TMPDIR)/ex.calls \
+		--with-examples $(TMPDIR)/ex2.calls
+
+	$(HTMLDOCCK) $(OUTPUT_DIR) src/lib.rs
+
+$(TMPDIR)/%.calls: $(TMPDIR)/libfoobar.rmeta
+	$(RUSTDOC) examples/$*.rs --crate-name $* --crate-type bin --output $(OUTPUT_DIR) \
+	  --extern foobar=$(TMPDIR)/libfoobar.rmeta \
+		-Z unstable-options \
+		--scrape-examples-output-path $@ \
+		--scrape-examples-target-crate foobar
+
+$(TMPDIR)/lib%.rmeta: src/lib.rs
+	$(RUSTC) src/lib.rs --crate-name $* --crate-type lib --emit=metadata

src/test/run-make/rustdoc-scrape-examples-multiple/examples/ex.rs

@@ -0,0 +1,4 @@
+fn main() {
+    foobar::ok();
+    foobar::ok();
+}

src/test/run-make/rustdoc-scrape-examples-multiple/examples/ex2.rs

@@ -0,0 +1,3 @@
+fn main() {
+    foobar::ok();
+}

src/test/run-make/rustdoc-scrape-examples-multiple/src/lib.rs

@@ -0,0 +1,4 @@
+// @has foobar/fn.ok.html '//*[@class="prev"]' ''
+// @has foobar/fn.ok.html '//*[@class="more-scraped-examples"]' ''
+
+pub fn ok() {}