Cleanup old CMake related docs in readme.md

The bit about CMAKE_MSVC_RUNTIME_LIBRARY has lost all context.
Originally it was related to OVERRIDE_MSVCCRT. Removing it fully
is more clear.

Cleanup the configure instructions. Using newer CMake cli.

Remove bit about the CMake GUI being tested. Doesn't make sense to
have in the README.md

Remove section about GLSLANG_TESTS. This documentation is now
outdated.

README.md

@@ -12,8 +12,6 @@
 
 4. `OGLCompiler` and `HLSL` stub libraries have been fully removed from the build.
 
-Users are encouraged to utilize the standard approach via [CMAKE_MSVC_RUNTIME_LIBRARY](https://cmake.org/cmake/help/latest/variable/CMAKE_MSVC_RUNTIME_LIBRARY.html).
-
 # Glslang Components and Status
 
 There are several components:
@@ -126,24 +124,24 @@ git clone https://github.com/KhronosGroup/glslang.git
 
 #### 3) Configure
 
-Assume the source directory is `$SOURCE_DIR` and the build directory is
-`$BUILD_DIR`. First ensure the build directory exists, then navigate to it:
+Assume the source directory is `$SOURCE_DIR` and the build directory is `$BUILD_DIR`.
+CMake will create the `$BUILD_DIR` for the user if it doesn't exist.
 
+First change your working directory:
 ```bash
-mkdir -p $BUILD_DIR
-cd $BUILD_DIR
+cd $SOURCE_DIR
 ```
 
 For building on Linux:
 
 ```bash
-cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX="$(pwd)/install" $SOURCE_DIR
+cmake -B $BUILD_DIR -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX="$(pwd)/install"
 # "Release" (for CMAKE_BUILD_TYPE) could also be "Debug" or "RelWithDebInfo"
 ```
 
 For building on Android:
 ```bash
-cmake $SOURCE_DIR -G "Unix Makefiles" -DCMAKE_INSTALL_PREFIX="$(pwd)/install" -DANDROID_ABI=arm64-v8a -DCMAKE_BUILD_TYPE=Release -DANDROID_STL=c++_static -DANDROID_PLATFORM=android-24 -DCMAKE_SYSTEM_NAME=Android -DANDROID_TOOLCHAIN=clang -DANDROID_ARM_MODE=arm -DCMAKE_MAKE_PROGRAM=$ANDROID_NDK_HOME/prebuilt/linux-x86_64/bin/make -DCMAKE_TOOLCHAIN_FILE=$ANDROID_NDK_HOME/build/cmake/android.toolchain.cmake
+cmake -B $BUILD_DIR -G "Unix Makefiles" -DCMAKE_INSTALL_PREFIX="$(pwd)/install" -DANDROID_ABI=arm64-v8a -DCMAKE_BUILD_TYPE=Release -DANDROID_STL=c++_static -DANDROID_PLATFORM=android-24 -DCMAKE_SYSTEM_NAME=Android -DANDROID_TOOLCHAIN=clang -DANDROID_ARM_MODE=arm -DCMAKE_MAKE_PROGRAM=$ANDROID_NDK_HOME/prebuilt/linux-x86_64/bin/make -DCMAKE_TOOLCHAIN_FILE=$ANDROID_NDK_HOME/build/cmake/android.toolchain.cmake
 # If on Windows will be -DCMAKE_MAKE_PROGRAM=%ANDROID_NDK_HOME%\prebuilt\windows-x86_64\bin\make.exe
 # -G is needed for building on Windows
 # -DANDROID_ABI can also be armeabi-v7a for 32 bit
@@ -152,12 +150,10 @@ cmake $SOURCE_DIR -G "Unix Makefiles" -DCMAKE_INSTALL_PREFIX="$(pwd)/install" -D
 For building on Windows:
 
 ```bash
-cmake $SOURCE_DIR -DCMAKE_INSTALL_PREFIX="$(pwd)/install"
+cmake -B $BUILD_DIR -DCMAKE_INSTALL_PREFIX="$(pwd)/install"
 # The CMAKE_INSTALL_PREFIX part is for testing (explained later).
 ```
 
-The CMake GUI also works for Windows (version 3.4.1 tested).
-
 Also, consider using `git config --global core.fileMode false` (or with `--local`) on Windows
 to prevent the addition of execution permission on files.
 
@@ -175,10 +171,6 @@ cmake --build . --config Release --target install
 If using MSVC, after running CMake to configure, use the
 Configuration Manager to check the `INSTALL` project.
 
-If you want to enable testing via CMake set `GLSLANG_TESTS=ON` when configuring the build.
-
-`GLSLANG_TESTS` is off by default to streamline the packaging / Vulkan SDK process.
-
 ### Building (GN)
 
 glslang can also be built with the [GN build system](https://gn.googlesource.com/gn/).