[MONGOCRYPT-876] Remove ENABLE_WINDOWS_STATIC_RUNTIME (mongodb#1115)

This simply removes the `ENABLE_WINDOWS_STATIC_RUNTIME` configuration parameter from the CMake project. CMake 3.15 offers a built-in way for users to control this aspect of the build, so it is not necessary that we offer it.

Author: vector-of-bool

CHANGELOG.md

@@ -1,5 +1,16 @@
 # ChangeLog
 
+## Unreleased
+
+### Removed
+
+- The configure-time CMake parameter `ENABLE_WINDOWS_STATIC_RUNTIME` has been
+  removed. Users that need the static MSVCRT library should instead set the
+  [`CMAKE_MSVC_RUNTIME_LIBRARY`][msvcrt] built-in CMake parameter when
+  configuring libmongocrypt.
+
+[msvcrt]: https://cmake.org/cmake/help/latest/variable/CMAKE_MSVC_RUNTIME_LIBRARY.html
+
 ## 1.17.1
 
 Add package for Debian Trixie.
@@ -202,7 +213,7 @@ This release makes backwards breaking changes to Queryable Encryption (QE) behav
 ## Warnings
 - This release has a severe bug in the context returned by `mongocrypt_ctx_rewrap_many_datakey_init` that may result in data corruption. Please upgrade to 1.5.2 before using `mongocrypt_ctx_rewrap_many_datakey_init`.
 ## Fixed
-- Update to use new payload for FLE 2.0 find. 
+- Update to use new payload for FLE 2.0 find.
 - Require contention factor.
 ## 1.5.0-rc2
 ### Fixed
@@ -222,7 +233,7 @@ This release makes backwards breaking changes to Queryable Encryption (QE) behav
 ## 1.5.0-rc0
 ## Fixed
 - Account for shared library rename.
-- Update to use new payload for FLE 2.0 find. 
+- Update to use new payload for FLE 2.0 find.
 
 ## 1.5.0-alpha2
 ## New Features

CMakeLists.txt

@@ -15,10 +15,6 @@ option (ENABLE_PIC
 option (ENABLE_BUILD_FOR_PPA "Maintainer-only option for preparing PPA build" OFF)
 option (ENABLE_ONLINE_TESTS "Enable online tests and the csfle utility. Requires libmongoc." ON)
 
-if (ENABLE_WINDOWS_STATIC_RUNTIME)
-   set (CMAKE_MSVC_RUNTIME_LIBRARY "MultiThreaded$<$<CONFIG:Debug>:Debug>")
-endif ()
-
 if (MINGW)
    # MSVCRT-based mingw-w64 GCC requires this macro to enable C99 format specifiers. This does not apply to UCRT-based
    # mingw-w64 GCC, but apply the workaround anyways until bson-compat.h no longer requires this.