Code replicated in compression and decompression moved to shared headers

`CHECK_F` macro moved to `error_private.h` (shared between `fse_compress.c` and `fse_decompress.c`). `ZSTD_limitCopy()` moved to `zstd_internal.h` (shared between `zstd_compress.c` and `zstd_decompress.c`). Erroneous build artefact `zstd.h` removed from repo.

lib/common/error_private.h

@@ -57,6 +57,10 @@ ERR_STATIC unsigned ERR_isError(size_t code) { return (code > ERROR(maxCode)); }
 
 ERR_STATIC ERR_enum ERR_getErrorCode(size_t code) { if (!ERR_isError(code)) return (ERR_enum)0; return (ERR_enum) (0-code); }
 
+/* check and forward error code */
+#define CHECK_V_F(e, f) size_t const e = f; if (ERR_isError(e)) return e
+#define CHECK_F(f)   { CHECK_V_F(_var_err__, f); }
+
 
 /*-****************************************
 *  Error Strings

lib/common/fse_decompress.c

@@ -31,11 +31,6 @@
 #define FSE_isError ERR_isError
 #define FSE_STATIC_ASSERT(c) DEBUG_STATIC_ASSERT(c)   /* use only *after* variable declarations */
 
-/* check and forward error code */
-#ifndef CHECK_F
-#define CHECK_F(f) { size_t const e = f; if (FSE_isError(e)) return e; }
-#endif
-
 
 /* **************************************************************
 *  Templates

lib/common/zstd_internal.h

@@ -248,6 +248,14 @@ void ZSTD_wildcopy(void* dst, const void* src, ptrdiff_t length, ZSTD_overlap_e
     }
 }
 
+MEM_STATIC size_t ZSTD_limitCopy(void* dst, size_t dstCapacity, const void* src, size_t srcSize)
+{
+    size_t const length = MIN(dstCapacity, srcSize);
+    if (length > 0) {
+        memcpy(dst, src, length);
+    }
+    return length;
+}
 
 /*-*******************************************
 *  Private declarations

lib/compress/fse_compress.c

@@ -625,11 +625,6 @@ size_t FSE_compress_usingCTable (void* dst, size_t dstSize,
 
 size_t FSE_compressBound(size_t size) { return FSE_COMPRESSBOUND(size); }
 
-#define CHECK_V_F(e, f) size_t const e = f; if (ERR_isError(e)) return e
-#ifndef CHECK_F
-#define CHECK_F(f)   { CHECK_V_F(_var_err__, f); }
-#endif
-
 /* FSE_compress_wksp() :
  * Same as FSE_compress2(), but using an externally allocated scratch buffer (`workSpace`).
  * `wkspSize` size must be `(1<<tableLog)`.

lib/compress/zstd_compress.c

@@ -3749,17 +3749,6 @@ static size_t ZSTD_nextInputSizeHint(const ZSTD_CCtx* cctx)
     return hintInSize;
 }
 
-#ifndef ZSTD_DECOMPRESS_INTERNAL_H /* zstd_decompress.c has the same function */
-MEM_STATIC size_t ZSTD_limitCopy(void* dst, size_t dstCapacity, const void* src, size_t srcSize)
-{
-    size_t const length = MIN(dstCapacity, srcSize);
-    if (length > 0) {
-        memcpy(dst, src, length);
-    }
-    return length;
-}
-#endif
-
 /** ZSTD_compressStream_generic():
  *  internal function for all *compressStream*() variants
  *  non-static, because can be called from zstdmt_compress.c

lib/decompress/zstd_decompress.c

@@ -1498,17 +1498,6 @@ size_t ZSTD_estimateDStreamSize_fromFrame(const void* src, size_t srcSize)
 
 /* *****   Decompression   ***** */
 
-#ifndef ZSTD_COMPRESS_H /* zstd_compress.c has the same function */
-MEM_STATIC size_t ZSTD_limitCopy(void* dst, size_t dstCapacity, const void* src, size_t srcSize)
-{
-    size_t const length = MIN(dstCapacity, srcSize);
-    if (length > 0) {
-        memcpy(dst, src, length);
-    }
-    return length;
-}
-#endif
-
 size_t ZSTD_decompressStream(ZSTD_DStream* zds, ZSTD_outBuffer* output, ZSTD_inBuffer* input)
 {
     const char* const src = (const char*)input->src;