Use CONFIG += silent to avoid the need to reset MAKEFLAGS

* When cmake custom commands invoke make, the make execution is silent.
  The MAKEFLAGS reset was to remove the silent flag, but it also lost
  the -j parallel build flags.
* Instead, we set qmake to silent mode (which it already was going to
  be), and that causes it to add echo statements to each rule that will
  be printed even when make is silent.

qrenderdoc/CMakeLists.txt

@@ -26,7 +26,7 @@ endif()
 # can do dependency checking and rebuild anything necessary.
 add_custom_command(OUTPUT QRenderDoc
 	COMMAND qmake "CONFIG+=${QMAKE_CONFIG}" "QMAKE_CC=${CMAKE_C_COMPILER}" "QMAKE_CXX=${CMAKE_CXX_COMPILER}" "QMAKE_LINK=${CMAKE_CXX_COMPILER}" "QMAKE_CXXFLAGS+=${warning_flags}" "QMAKE_CXXFLAGS+=${QMAKE_CXXFLAGS}" "QMAKE_LFLAGS+=${QMAKE_LDFLAGS}" "DEFINES+=GIT_COMMIT_HASH_LITERAL=${GIT_COMMIT_HASH}" "DESTDIR=${output_dir}" ${CMAKE_CURRENT_SOURCE_DIR}
-	COMMAND MAKEFLAGS= make --no-print-directory)
+	COMMAND $(MAKE))
 add_custom_target(build-qrenderdoc ALL DEPENDS QRenderDoc DEPENDS renderdoc)
 
 install (PROGRAMS ${output_dir}/qrenderdoc DESTINATION bin)

qrenderdoc/qrenderdoc.pro

@@ -6,6 +6,8 @@
 
 QT       += core gui widgets
 
+CONFIG   += silent
+
 lessThan(QT_MAJOR_VERSION, 5): error("requires Qt 5")
 
 equals(QT_MAJOR_VERSION, 5): lessThan(QT_MINOR_VERSION, 6): error("requires Qt 5.6")