g_free accepts NULL so these are pointless unless they are extremely
performance critical.

tools/check-gfrees: Checked g_free at plugins/applix/applix-read.c:1631
tools/check-gfrees: Checked g_free at plugins/excel/ms-chart.c:2688
tools/check-gfrees: Checked g_free at plugins/excel/ms-excel-read.c:3398
tools/check-gfrees: Checked g_free at plugins/excel/ms-excel-read.c:3400
tools/check-gfrees: Checked g_free at plugins/excel/ms-excel-read.c:3402
tools/check-gfrees: Checked g_free at plugins/excel/ms-excel-read.c:3404
tools/check-gfrees: Checked g_free at plugins/html/latex.c:1347
tools/check-gfrees: Checked g_free at plugins/mps/mps.c:608
tools/check-gfrees: Checked g_free at plugins/mps/mps.c:613
tools/check-gfrees: Checked g_free at plugins/openoffice/openoffice-write.c:384
tools/check-gfrees: Checked g_free at plugins/sc/sc.c:202
tools/check-gfrees: Checked g_free at src/collect.c:553
tools/check-gfrees: Checked g_free at src/commands.c:1483
tools/check-gfrees: Checked g_free at src/complete.c:57
tools/check-gfrees: Checked g_free at src/complete.c:89
tools/check-gfrees: Checked g_free at src/complex.c:59
tools/check-gfrees: Checked g_free at src/complex.c:60
tools/check-gfrees: Checked g_free at src/complex.c:61
tools/check-gfrees: Checked g_free at src/func.c:1607
tools/check-gfrees: Checked g_free at src/graph.c:368
tools/check-gfrees: Checked g_free at src/graph.c:755
tools/check-gfrees: Checked g_free at src/regression.c:957
tools/check-gfrees: Checked g_free at src/regression.c:959
tools/check-gfrees: Checked g_free at src/regression.c:961
tools/check-gfrees: Checked g_free at src/sheet-object-cell-comment.c:359
tools/check-gfrees: Checked g_free at src/sheet-object-cell-comment.c:378
tools/check-gfrees: Checked g_free at src/sheet-object-image.c:210
tools/check-gfrees: Checked g_free at src/sheet-object-widget.c:248
tools/check-gfrees: Checked g_free at src/sheet-object-widget.c:338
tools/check-gfrees: Checked g_free at src/sheet-object-widget.c:359
tools/check-gfrees: Checked g_free at src/sheet-object-widget.c:1325
tools/check-gfrees: Checked g_free at src/sheet-object-widget.c:1762
tools/check-gfrees: Checked g_free at src/stf-parse.c:177
tools/check-gfrees: Checked g_free at src/stf-parse.c:179
tools/check-gfrees: Checked g_free at src/stf-parse.c:181
tools/check-gfrees: Checked g_free at src/stf-parse.c:964
tools/check-gfrees: Checked g_free at src/workbook-edit.c:219
tools/check-gfrees: Checked g_free at src/workbook-view.c:400
tools/check-gfrees: Checked g_free at src/workbook-view.c:584
tools/check-gfrees: Checked g_free at src/workbook-view.c:588
tools/check-gfrees: Checked g_free at src/xml-io.c:456
tools/check-gfrees: Checked g_free at src/xml-io.c:464
tools/check-gfrees: Checked g_free at src/xml-io.c:472
tools/check-gfrees: Checked g_free at src/xml-sax-read.c:1597
tools/check-gfrees: Checked g_free at src/dialogs/dialog-doc-metadata.c:1238
tools/check-gfrees: Checked g_free at src/dialogs/dialog-doc-metadata.c:1407
tools/check-gfrees: Checked g_free at src/dialogs/dialog-preferences.c:192
tools/check-gfrees: Checked g_free at src/dialogs/dialog-preferences.c:235
tools/check-gfrees: Checked g_free at src/dialogs/dialog-preferences.c:289
tools/check-gfrees: Checked g_free at src/dialogs/dialog-solver.c:860
tools/check-gfrees: Checked g_free at src/dialogs/dialog-stf-format-page.c:572
tools/check-gfrees: Checked g_free at src/tools/analysis-tools.c:169
tools/check-gfrees: Checked g_free at src/tools/dao.c:146
tools/check-gfrees: Checked g_free at tools/gconf-schemas-to-win32-reg.c:209
tools/check-gfrees: Checked g_free at tools/gconf-schemas-to-win32-reg.c:279