Document C++Builder usage in NOTES-WINDOWS.md

Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Dmitry Belyavskiy <beldmit@gmail.com>
(Merged from https://github.com/openssl/openssl/pull/13540)

NOTES-WINDOWS.md

@@ -2,6 +2,8 @@ Notes for Windows platforms
 ===========================
 
  - [Native builds using Visual C++](#native-builds-using-visual-c++)
+ - [Native builds using Embarcadero C++Builder](
+   #native-builds-using-embarcadero-c++-builder)
  - [Native builds using MinGW](#native-builds-using-mingw)
  - [Linking native applications](#linking-native-applications)
  - [Hosted builds using Cygwin](#hosted-builds-using-cygwin)
@@ -13,6 +15,8 @@ There are various options to build and run OpenSSL on the Windows platforms.
 To build a native OpenSSL you can either use:
 
     Microsoft Visual C++ (MSVC) C compiler on the command line
+or
+    Embarcadero C++Builder
 or
     MinGW cross compiler
     run on the GNU-like development environment MSYS2
@@ -119,6 +123,30 @@ Special notes for Universal Windows Platform builds, aka VC-*-UWP
    "vcvarsall.bat" before you compile. For example, if you want to build
    "arm64" builds, you should run "vcvarsall.bat x86_arm64 uwp".
 
+Native builds using Embarcadero C++Builder
+=========================================
+
+This toolchain (a descendant of Turbo/Borland C++) is an alternative to MSVC.
+OpenSSL currently includes an experimental 32-bit static-build configuration
+targeting the Clang-based compiler (bcc32c.exe) in v10.3.3 Community Edition.
+<https://www.embarcadero.com/products/cbuilder/starter>
+
+ 1. Install Perl.
+
+ 2. Open the RAD Studio Command Prompt.
+
+ 3. Go to the root of the OpenSSL source directory and run:
+    perl Configure BC-32 --prefix=%CD%
+
+ 4. make -N
+
+ 5. Build your program against this OpenSSL:
+    * Set your include search path to the "include" subdirectory of OpenSSL.
+    * Set your library search path to the OpenSSL source directory.
+
+Note that this is very experimental. Support for 64-bit, dynamic library, and
+other Configure options is still pending.
+
 Native builds using MinGW
 =========================