cmake: Check dependencies for Linux Qt package

Currently Qt will download whether or not the target system supports the
package. Normally this isn't an issue since the package manager would
work out the dependencies for us, but in this case we must make sure
everything is in place before downloading the package.

This checks for the package's requirements, as well as tries to provides
hints as to what is required on some of the more cryptic dependencies.

CMakeLists.txt

@@ -253,11 +253,82 @@ if(ENABLE_QT)
 
     # Check for system Qt on Linux, fallback to bundled Qt
     if (${CMAKE_SYSTEM_NAME} STREQUAL "Linux")
-        if (NOT YUZU_USE_BUNDLED_QT)
-            find_package(Qt5 ${QT_VERSION} COMPONENTS Widgets QUIET)
-            if (NOT Qt5_FOUND)
-                set(YUZU_USE_BUNDLED_QT ON CACHE BOOL "Download bundled Qt" FORCE)
+        find_package(Qt5 ${QT_VERSION} COMPONENTS Widgets)
+        if (NOT Qt5_FOUND OR YUZU_USE_BUNDLED_QT)
+            # Check for dependencies, then enable bundled Qt download
+
+            # Check that the system GLIBCXX version is compatible
+            find_program(OBJDUMP objdump)
+            if ("${OBJDUMP}" STREQUAL "OBJDUMP-NOTFOUND")
+                message(FATAL_ERROR "Required program `objdump` not found.")
             endif()
+            find_library(LIBSTDCXX libstdc++.so.6)
+            execute_process(
+                COMMAND
+                    ${OBJDUMP} -T ${LIBSTDCXX}
+                COMMAND
+                    grep GLIBCXX_3.4.28
+                COMMAND
+                    sed "s/[0-9a-f]*.*  //"
+                COMMAND
+                    sed "s/ .*//"
+                COMMAND
+                    sort -u
+                OUTPUT_VARIABLE
+                    GLIBCXX_MET
+            )
+            if (NOT GLIBCXX_MET)
+                message(FATAL_ERROR "Qt too old or not found, and bundled Qt package is not \
+                    compatible with this system. Either install Qt ${QT_VERSION}, or provide the path \
+                    to Qt by setting the variable Qt5_ROOT.")
+            endif()
+
+            # Check for headers
+            Include(FindPkgConfig REQUIRED)
+            pkg_check_modules(QT_DEP_GLU QUIET glu>=9.0.0)
+            if (NOT QT_DEP_GLU_FOUND)
+                message(FATAL_ERROR "Qt bundled pacakge dependency `glu` not found. \
+                    Perhaps `libglu1-mesa-dev` needs to be installed?")
+            endif()
+            pkg_check_modules(QT_DEP_MESA QUIET dri>=20.0.8)
+            if (NOT QT_DEP_MESA_FOUND)
+                message(FATAL_ERROR "Qt bundled pacakge dependency `dri` not found. \
+                    Perhaps `mesa-common-dev` needs to be installed?")
+            endif()
+
+            # Check for X libraries
+            set(BUNDLED_QT_REQUIREMENTS
+                libxcb-icccm.so.4
+                libxcb-image.so.0
+                libxcb-keysyms.so.1
+                libxcb-randr.so.0
+                libxcb-render-util.so.0
+                libxcb-render.so.0
+                libxcb-shape.so.0
+                libxcb-shm.so.0
+                libxcb-sync.so.1
+                libxcb-xfixes.so.0
+                libxcb-xinerama.so.0
+                libxcb-xkb.so.1
+                libxcb.so.1
+                libxkbcommon-x11.so.0
+                libxkbcommon.so.0
+            )
+            set(UNRESOLVED_QT_DEPS "")
+            foreach (REQUIREMENT ${BUNDLED_QT_REQUIREMENTS})
+                find_library(BUNDLED_QT_${REQUIREMENT} ${REQUIREMENT})
+                if ("${BUNDLED_QT_${REQUIREMENT}}" STREQUAL "BUNDLED_QT_${REQUIREMENT}-NOTFOUND")
+                    set(UNRESOLVED_QT_DEPS ${UNRESOLVED_QT_DEPS} ${REQUIREMENT})
+                endif()
+                unset(BUNDLED_QT_${REQUIREMENT})
+            endforeach()
+            unset(BUNDLED_QT_REQUIREMENTS)
+
+            if (NOT "${UNRESOLVED_QT_DEPS}" STREQUAL "")
+                message(FATAL_ERROR "Bundled Qt package missing required dependencies: ${UNRESOLVED_QT_DEPS}")
+            endif()
+
+            set(YUZU_USE_BUNDLED_QT ON CACHE BOOL "Download bundled Qt" FORCE)
         endif()
         if (YUZU_USE_BUNDLED_QT)
             # Binary package currently does not support Qt webengine, so make sure it's disabled