Merge bitcoin/bitcoin#33379: cmake: Fix regression in secp256k1.cmake

9193c3e434 cmake: Fix regression in `secp256k1.cmake` (Hennadii Stepanov)

Pull request description:

  This PR fixes a regression introduced in https://github.com/bitcoin/bitcoin/pull/33101 (mea culpa).

  From the CMake [docs](https://cmake.org/cmake/help/latest/command/enable_language.html):
  > The following restrictions apply to where `enable_language()` may be called:
  >
  >    - It must be called in file scope, not in a function call.

  Fixes https://github.com/bitcoin/bitcoin/issues/33153.

ACKs for top commit:
  TheCharlatan:
    ACK 9193c3e434
  furszy:
    ACK 9193c3e434

Tree-SHA512: 5f9ca2209af195a5eefefffdceae1acf650db29b371616f803b482a6b8acc4e87acc66714488520ef91d06ad4436438d9030be9979bd4c482cb5d1ce65b7f67e

cmake/secp256k1.cmake

@@ -2,6 +2,8 @@
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or https://opensource.org/license/mit/.
 
+enable_language(C)
+
 function(add_secp256k1 subdir)
   message("")
   message("Configuring secp256k1 subtree...")
@@ -30,7 +32,6 @@ function(add_secp256k1 subdir)
   string(STRIP "${SECP256K1_APPEND_LDFLAGS} ${APPEND_LDFLAGS}" SECP256K1_APPEND_LDFLAGS)
   set(SECP256K1_APPEND_LDFLAGS ${SECP256K1_APPEND_LDFLAGS} CACHE STRING "" FORCE)
   # We want to build libsecp256k1 with the most tested RelWithDebInfo configuration.
-  enable_language(C)
   foreach(config IN LISTS CMAKE_BUILD_TYPE CMAKE_CONFIGURATION_TYPES)
     if(config STREQUAL "")
       continue()