Compiler fixes for gcc 10

This patch fixes a few compile warnings/errors that now occur when using gcc
10+.

Also, the Makefile.rules check to turn off partial inlining in gcc versions
greater or equal to 8.2.1 had a bug where it only it only checked against
versions with at least 3 numbers (ex: 8.2.1 vs 10). This patch now ensures
any version above the specified version is correctly compared.

Change-Id: I54718496eb0c3ce5bd6d427cd279a29e8d2825f9