[blender] Disable creation of "dna.txt"

Developers who want to enable it can either:

- *Temporarily* set ASSIMP_BUILD_BLENDER_DEBUG_DNA=1 in BlenderDNA.h, or
- *Temporarily* define ASSIMP_BUILD_BLENDER_DEBUG_DNA=1 on the build command line.

Addresses #3886.

code/AssetLib/Blender/BlenderDNA.cpp

@@ -200,7 +200,7 @@ void DNAParser::Parse() {
 
     ASSIMP_LOG_DEBUG_F("BlenderDNA: Got ", dna.structures.size(), " structures with totally ", fields, " fields");
 
-#ifdef ASSIMP_BUILD_BLENDER_DEBUG
+#if ASSIMP_BUILD_BLENDER_DEBUG_DNA
     dna.DumpToFile();
 #endif
 
@@ -208,7 +208,7 @@ void DNAParser::Parse() {
     dna.RegisterConverters();
 }
 
-#ifdef ASSIMP_BUILD_BLENDER_DEBUG
+#if ASSIMP_BUILD_BLENDER_DEBUG_DNA
 
 #include <fstream>
 // ------------------------------------------------------------------------------------------------
@@ -237,7 +237,7 @@ void DNA ::DumpToFile() {
 
     ASSIMP_LOG_INFO("BlenderDNA: Dumped dna to dna.txt");
 }
-#endif
+#endif // ASSIMP_BUILD_BLENDER_DEBUG_DNA
 
 // ------------------------------------------------------------------------------------------------
 /*static*/ void DNA ::ExtractArraySize(

code/AssetLib/Blender/BlenderDNA.h

@@ -59,6 +59,13 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #define ASSIMP_BUILD_BLENDER_DEBUG
 #endif
 
+// set this to non-zero to dump BlenderDNA stuff to dna.txt.
+// you could set it on the assimp build command line too without touching it here.
+// !!! please make sure this is set to 0 in the repo !!!
+#ifndef ASSIMP_BUILD_BLENDER_DEBUG_DNA
+#define ASSIMP_BUILD_BLENDER_DEBUG_DNA 0
+#endif
+
 // #define ASSIMP_BUILD_BLENDER_NO_STATS
 
 namespace Assimp {
@@ -495,7 +502,7 @@ public:
             const Structure &structure,
             const FileDatabase &db) const;
 
-#ifdef ASSIMP_BUILD_BLENDER_DEBUG
+#if ASSIMP_BUILD_BLENDER_DEBUG_DNA
     // --------------------------------------------------------
     /** Dump the DNA to a text file. This is for debugging purposes.
      *  The output file is `dna.txt` in the current working folder*/