[libc][NFC] Remove extra slash in path in libc/CMakeLists.txt

Remove extra `/` in path to match the include filepath from the previous
line.

Differential Revision: https://reviews.llvm.org/D112476

GitOrigin-RevId: 46c82753f6a41ce289947b25fb5c65138764f7b3
diff --git a/CMakeLists.txt b/CMakeLists.txt
index bfab38e..234e932 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -95,7 +95,7 @@
 if(EXISTS "${LIBC_SOURCE_DIR}/config/${LIBC_TARGET_OS}/${LIBC_TARGET_ARCHITECTURE}/headers.txt")
   include("${LIBC_SOURCE_DIR}/config/${LIBC_TARGET_OS}/${LIBC_TARGET_ARCHITECTURE}/headers.txt")
 elseif(EXISTS "${LIBC_SOURCE_DIR}/config/${LIBC_TARGET_OS}/headers.txt")
-  include("${LIBC_SOURCE_DIR}/config/${LIBC_TARGET_OS}//headers.txt")
+  include("${LIBC_SOURCE_DIR}/config/${LIBC_TARGET_OS}/headers.txt")
 endif()
 
 set(TARGET_ENTRYPOINT_NAME_LIST "")