Documenting why unit tests are in release build.

qgroundcontrol.pro

@@ -749,14 +749,12 @@ SOURCES += \
 
 #
 # Unit Test specific configuration goes here
-#
-# FIXME: These files should only be enabled on the Debug build, but that is currently broken as of Qt5.3.1 on Windows,
-#        so we just always compile them.
-#ReleaseBuild {
-    INCLUDEPATH += \
+# We'd ideally only build this code as part of a Debug build, but qmake doesn't allow
+# for Debug-only files when generating Visual Studio projects [QTBUG-40351]
+INCLUDEPATH += \
 	src/qgcunittest
 
-    HEADERS += \
+HEADERS += \
 	src/qgcunittest/AutoTest.h \
 	src/qgcunittest/UASUnitTest.h \
 	src/qgcunittest/MockUASManager.h \
@@ -771,7 +769,7 @@ SOURCES += \
 	src/qgcunittest/TCPLoopBackServer.h \
 	src/qgcunittest/QGCUASFileManagerTest.h
 
-    SOURCES += \
+SOURCES += \
 	src/qgcunittest/UASUnitTest.cc \
 	src/qgcunittest/MockUASManager.cc \
 	src/qgcunittest/MockUAS.cc \
@@ -783,4 +781,3 @@ SOURCES += \
 	src/qgcunittest/TCPLinkTest.cc \
 	src/qgcunittest/TCPLoopBackServer.cc \
 	src/qgcunittest/QGCUASFileManagerTest.cc
\ No newline at end of file
-#}