CMake: Build with immediate binding/full relro

Doing a full xsave/xrstor the first time a library function is
called is completely bonkers. Plus the obvious security issues
with the PLT being writable.

And people think this OS is faster than Windows. Even with immediate
binding it's still slower, since it's a single indirect call on
Windows, versus a direct call+indirect jump here.

CMakeLists.txt

@@ -42,10 +42,13 @@ include(DuckStationDependencies)
 include(DuckStationCompilerRequirement)
 
 # Enable PIC on Linux, otherwise the builds do not support ASLR.
+# Also force immediate binding of all symbols, glibc and its
+# xsave/xrstor on first shared library call is bonkers.
 if(LINUX OR BSD)
   include(CheckPIESupported)
   check_pie_supported()
   set(CMAKE_POSITION_INDEPENDENT_CODE TRUE)
+  set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -Wl,-z,now,-z,relro")
 endif()
 
 # Force debug symbols for Linux builds.

CMakeModules/DuckStationBuildSummary.cmake

@@ -8,6 +8,7 @@ message(STATUS "Build Type: ${CMAKE_BUILD_TYPE}")
 string(TOUPPER "${CMAKE_BUILD_TYPE}" CMAKE_BUILD_TYPE_UPPER)
 message(STATUS "C Flags: ${CMAKE_C_FLAGS} ${CMAKE_C_FLAGS_${CMAKE_BUILD_TYPE_UPPER}}")
 message(STATUS "CXX Flags: ${CMAKE_CXX_FLAGS} ${CMAKE_CXX_FLAGS_${CMAKE_BUILD_TYPE_UPPER}}")
+message(STATUS "Linker Flags: ${CMAKE_EXE_LINKER_FLAGS} ${CMAKE_EXE_LINKER_FLAGS_${CMAKE_BUILD_TYPE_UPPER}}")
 
 if(ENABLE_OPENGL)
   message(STATUS "Building with OpenGL support.")