Change to use -Og in debug builds instead of -O0
Better debugging/warning
basic_flags := -std=c99 -pipe -Wall -Wpedantic -Wextra -Werror=implicit-function-declaration -D_XOPEN_SOURCE_EXTENDED=1
-debug_flags := -DDEBUG -O0 -ggdb -feliminate-unused-debug-symbols
+debug_flags := -DDEBUG -Og -ggdb -feliminate-unused-debug-symbols
sanitize_flags := -fsanitize=address -fsanitize=undefined
# note: -fsanitize=leak not available on at least Mac 10.12
release_flags := -DNDEBUG -O2 -s -D_FORTIFY_SOURCE=2 -fstack-protector-strong -fpie -Wl,-pie
