Fix final simgear GCC warnings.

simgear/io/sg_binobj.cxx

@@ -1006,9 +1006,13 @@ bool SGBinObject::write_ascii( const string& base, const string& name,
     fclose(fp);
 
     string command = "gzip --force --best " + file.str();
-    system(command.c_str());
+    int err = system(command.c_str());
+    if (err)
+    {
+        cout << "ERROR: gzip " << file.str() << " failed!" << endl;
+    }
 
-    return true;
+    return (err == 0);
 }
 
 void SGBinObject::read_properties(gzFile fp, int nproperties)

simgear/screen/screen-dump.cxx

@@ -65,10 +65,16 @@ bool sg_glWritePPMFile(const char *filename, GLubyte *buffer, int win_width, int
 	    for (k = 0; k < RGB3; k++)
 		ibuffer[q++] = (unsigned char)
 		    *(buffer + (pixelSize*((win_height-1-i)*win_width+j)+k));
-    fwrite(ibuffer, sizeof(unsigned char), RGB3*win_width*win_height, fp);
+    int written = fwrite(ibuffer, sizeof(unsigned char), RGB3*win_width*win_height, fp);
     fclose(fp);
     free(ibuffer);
 
+    if ( written != RGB3*win_width*win_height )
+    {
+        printf("Warning: failed to write %s. File truncated.\n", filename);
+        return false;
+    }
+
     printf("wrote file '%s' (%d x %d pixels, %d bytes)\n",
 	   filename, win_width, win_height, RGB3*win_width*win_height);
     return true;

simgear/sound/sample_openal.hxx

@@ -85,7 +85,7 @@ public:
     virtual ~SGSoundSample ();
 
     /**
-     * Detect wheter this audio sample holds the information of a sound file.
+     * Detect whether this audio sample holds the information of a sound file.
      * @return Return true if this audio sample is to be constructed from a file.
      */
     inline bool is_file() const { return _is_file; }
@@ -103,7 +103,7 @@ public:
     }
 
     /**
-     * Test if static dataa of audio sample configuration has changed.
+     * Test if static data of audio sample configuration has changed.
      * Calling this function will reset the flag so calling it a second
      * time in a row will return false.
      * @return Return true is the static data has changed in the mean time.

simgear/timing/timezone.cxx

@@ -143,7 +143,7 @@ SGTimeZoneContainer::SGTimeZoneContainer(const char *filename)
     errno = 0;
 
     while (1) {
-        fgets(buffer, 256, infile);
+        (void) fgets(buffer, 256, infile);
         if (feof(infile)) {
             break;
         }