Add 'override' keyword before adding to CFLAGS

[jsarenik]

There is an important command line argument adding directory '.' to be searched for header files.

$ make -n | grep -m1 ^cc
cc -O2 -I. -D_GNU_SOURCE -std=gnu99 -Wall -pedantic -Wno-format-security \
   -Wno-pointer-sign   -c -o alloc.o alloc.c

Without this patch, whenever CFLAGS are set by a command line argument, the include directory (along with other options) is missing:

$ make CFLAGS="-s" -n | grep -m1 ^cc
cc -s   -c -o alloc.o alloc.c

After this patch:

$ make CFLAGS="-s" -n | grep -m1 ^cc
cc -s -I. -D_GNU_SOURCE -std=gnu99 -Wall -pedantic -Wno-format-security \
   -Wno-pointer-sign   -c -o alloc.o alloc.c

The rationale is that when someone wants to add custom CFLAGS and is compiling loksh with musl libc, it is much easier to just add those CFLAGS to the existing set. When someone wants to debug and redefine CFLAGS completely, they will have to delete word "override" in the Makefile now. The logic before applying this patch was reversed and the change required to be done in Makefile was not as obvious as now.

https://www.gnu.org/software/make/manual/html_node/Override-Directive.html#Override-Directive

[dimkr]

I learned something new today. Thanks!