Correctly handle structured variables that include FB and external FBs (example: FB1.FB2.extFB3.FB4.extFB5.extFB6.structvar.field1 := 42;) (this commit fixes only ST code. TODO: IL and SFC)

AM_CXXFLAGS = -g -Wall -Wpointer-arith -Wwrite-strings -Wno-unused