Fix annoying compiler warnings

panda/src/gobj/shader.cxx

@@ -1033,11 +1033,11 @@ cg_release_resources() {
 //  Description: xyz
 ////////////////////////////////////////////////////////////////////
 CGprogram Shader::
-cg_compile_entry_point(char *entry, const ShaderCaps &caps, bool fshader)
+cg_compile_entry_point(const char *entry, const ShaderCaps &caps, bool fshader)
 {
   CGprogram prog;
   CGerror err;
-  char *compiler_args[100];
+  const char *compiler_args[100];
   int nargs = 0;
   int active = fshader ? caps._active_fprofile : caps._active_vprofile;
   int ultimate = fshader ? caps._ultimate_fprofile : caps._ultimate_vprofile;

panda/src/gobj/shader.h

@@ -257,7 +257,7 @@ public:
  private:
   ShaderArgType cg_parameter_type(CGparameter p);
   ShaderArgDir  cg_parameter_dir(CGparameter p);
-  CGprogram     cg_compile_entry_point(char *entry, const ShaderCaps &caps, bool fshader);
+  CGprogram     cg_compile_entry_point(const char *entry, const ShaderCaps &caps, bool fshader);
   bool          cg_analyze_entry_point(CGprogram prog, bool fshader);
   bool          cg_analyze_shader(const ShaderCaps &caps);
   bool          cg_compile_shader(const ShaderCaps &caps);

panda/src/gobj/vertexDataPage.cxx

@@ -404,7 +404,7 @@ make_resident() {
 #endif
 
     z_source.opaque = Z_NULL;
-    z_source.msg = "no error message";
+    z_source.msg = (char *) "no error message";
 
     z_source.next_in = (Bytef *)(char *)_page_data;
     z_source.avail_in = _size;
@@ -497,7 +497,7 @@ make_compressed() {
 #endif
 
     z_dest.opaque = Z_NULL;
-    z_dest.msg = "no error message";
+    z_dest.msg = (char *) "no error message";
     
     int result = deflateInit(&z_dest, vertex_data_compression_level);
     if (result < 0) {

panda/src/gobj/vertexDataSaveFile.cxx

@@ -131,7 +131,10 @@ VertexDataSaveFile(const Filename &directory, const string &prefix,
     if (result == 0) {
       // We've got the file.  Truncate it first, for good measure, in
       // case there's an old version of the file we picked up.
-      ftruncate(_fd, 0);
+      if (ftruncate(_fd, 0) < 0) {
+        gobj_cat.warning()
+          << "Couldn't truncate vertex data save file.\n";
+      }
 
       // On Unix, it's safe to unlink (delete) the temporary file
       // after it's been opened.  The file remains open, but