Revert "Forgot about Makefile.in"

This reverts commit 01fcd28c914f2e7a80e2c0a6404f6c4dbdc76834.
Removed `malloc` checking

Autotools fails to determine properly `malloc` presence when cross
compiling 32bit applications on x84-64 host.
Made `libindexer` cnages persist after `automake` invocation

Just moved changes from former `src/Makefile.in` to `src/Makefile.am`