Enable ASM language for zstd huf_decompress_amd64.S

Without enable_language(ASM) in CMakeLists, CMake silently drops the
.S file from the build tree. On x86-64 Linux and macOS the C side of
libzstd still references the symbols exported by the assembly file
(HUF_decompress4X1_usingDTable_internal_fast_asm_loop and its 4X2
sibling), so the final link fails with "Undefined symbols for
architecture x86_64" whenever the host matches ARCH_AMD64 AND NOT
WIN32. Linux x86-64 shows the same failure once the build actually
reaches the link step.

ARM64 and Windows are unaffected because they skip the .S file and
set ZSTD_DISABLE_ASM=1, routing everything through the C fallback.
The asmlib subdirectory's enable_language(ASM_NASM) is separate --
NASM is Intel-syntax and only handles Agner Fog's .asm files.

Author: bluestreak01

core/CMakeLists.txt

@@ -1,6 +1,12 @@
 cmake_minimum_required(VERSION 3.5)
 project(questdb)
 
+# Required for zstd's huf_decompress_amd64.S to be assembled. Without this,
+# CMake silently drops the .S file from the build and the link fails at
+# _HUF_decompress4X1_usingDTable_internal_fast_asm_loop etc. (The asmlib
+# subdirectory enables ASM_NASM separately for Agner Fog's .asm files.)
+enable_language(ASM)
+
 include(ExternalProject)
 
 set(CMAKE_CXX_STANDARD 17)