Fix segmentation fault in Logcollector

[vikman90]

Related issue
#3992

Description

We changed the method to prevent Logcollector from monitoring multiple hard links to the same file.

Instead of finding duplicate files on startup and removing one of the entries, now Logcollector searches for duplicate files on file checking. This stage is performed every logcollector.vcheck_files seconds.

Since two different devices may have the same inode, Logcollector finds duplicate "device:inode" pairs.

Tests

We tested file creation and deletion, including soft and hard links, on these setting combinations:

1. A wildcarded <location>.
2. Multiple hardcoded <location> stanzas.
3. Combining wildcarded and time pattern-based <location> stanzas.

• Compilation without warnings in every supported platform
  • Linux
  • Windows
  • MAC OS X
• Source installation
• Package installation
• Source upgrade
• Package upgrade
• Review logs syntax and correct language
• QA templates contemplate the added capabilities

• Memory tests for Linux
  • Scan-build report
  • Coverity
  • Valgrind (memcheck and descriptor leaks check)
  • Dr. Memory
  • AddressSanitizer
• Memory tests for Windows
  • Scan-build report
  • Coverity
  • Dr. Memory
• Memory tests for macOS
  • Scan-build report
  • Leaks
  • AddressSanitizer

• Stress test for affected components