Fix position issue of stext. Sometime, stext does not show at correct position. After some study, it is caused by a typo in the code of create scaled font (make_scaled_font_face()). The typo causes a fault in compute transform matrix for scale fonts.

m4datadir = $(datadir)/mb
dist_m4data_DATA = foreach.m4 mb_c_header.m4 mb_c_source.m4
dist_bin_SCRIPTS = svg2code.py