Handle LINKAGE SECTION and PROCEDURE DIVISION USING; skip ENTRY statements

Summary

This change updates the cobolcheck Generator to properly handle COBOL programs that declare a LINKAGE SECTION, use a multi-line PROCEDURE DIVISION USING clause, and include ENTRY statements (e.g., DLITCBL) that reference LINKAGE variables. It also adds a focused test program and test cases to validate behavior.

Changes

• Introduce state to track multi-line clauses in Generator:

  • skipUsingClauseLines and skipEntryStatementLines.

• Add processLinkageSectionFix(String sourceLine) to:

  • Skip LINKAGE SECTION line entirely.

  • Normalize PROCEDURE DIVISION USING ... to PROCEDURE DIVISION. while:

    • Preserving sequence area and indentation.
    • Skipping subsequent USING lines until the terminating period for multi-line clauses.

  • Detect and skip ENTRY statements that reference LINKAGE variables (single- and multi-line), resuming after the terminating period.

• Route lines through the new processing step before writing:

  • Replace direct writeLine(sourceLine) with the processed result, writing only when non-null.

• Add a COBOL sample program to exercise LINKAGE + USING + ENTRY:

  • src/main/cobol/TEST-LINKAGE.CBL (new).

• Add tests:

  • src/test/cobol/TEST-LINKAGE/TestLinkageSection.cut (new) with two test cases covering main and an additional entry point behavior.

Testing

• New COBOL program TEST-LINKAGE.CBL exercises LINKAGE, PROCEDURE DIVISION USING, and ENTRY scenarios.

• New cut tests:

  • Main entry point increments WS-COUNTER to 1 and sets WS-WORK-AREA to "MAIN ENTRY".
  • Secondary entry point increments WS-COUNTER to 10 and sets WS-WORK-AREA to "ENTRY POINT".

These validate that generation proceeds correctly without emitting LINKAGE/USING/ENTRY constructs while preserving program flow for testing.