Minor .gitignore tweaks based on IntelliJ IDEA experience on MacOS

Motivation:

* Builds produce more target directories than are listed explicitly in .gitignore.
* Builds can produce a file dependency-reduced-pom.xml which shows up as "untracked."

Modifications:

* Ignore all target/ directories.
* Ignore generated file dependency-reduced-pom.xml.
* Add missing EOL to EOF.

Result:

* Fewer untracked files in working repositories.

Target: master
Requires-notes: no
Requires-book: no
Patch: https://rb.dcache.org/r/14208/
Acked-by: Lea, Tigran

.gitignore

@@ -1,8 +1,5 @@
 ##  Ignore maven-generated directories and their contents.
-/modules/*/target/
-/packages/*/target/
-/plugins/*/target/
-/docs/*/target/
+target/
 
 ## Ignore Eclipse-generated files and directories
 ## The globbed version does not work on Mac OS X.9.
@@ -40,3 +37,6 @@
 
 # Ignoring .reviewboardrc file
 .reviewboardrc
+
+# Ignore generated XML in the source area:
+/modules/benchmarks/dependency-reduced-pom.xml