Revert "Do not include libgcc_mock"

This reverts commit 85554e3.

Author: yutannihilation

configure.win

@@ -16,6 +16,7 @@ fi
 
 # To address the change of the toolchain on R 4.2
 BEFORE_CARGO_BUILD="${BEFORE_CARGO_BUILD}"' export CARGO_TARGET_X86_64_PC_WINDOWS_GNU_LINKER="$(CARGO_LINKER)" \&\&'
+BEFORE_CARGO_BUILD="${BEFORE_CARGO_BUILD}"' export LIBRARY_PATH="$${LIBRARY_PATH};$(CURDIR)/$(LIBDIR)/libgcc_mock" \&\&'
 
 # If it's on CRAN, a package is not allowed to write in any other place than the
 # temporary directory on installation. So, we need to tweak Makevars to make the