Fails with Zig as a C compiler (Does not respect existing value of `CC` in Windows)

[eamonburns]

I tried using Zig as a C compiler by setting CC to zig cc:

$env:CC = "zig cc"
make

But I get the following error:

cmd /C mkdir build
gcc -O3 -Wall -fpic -std=gnu99 -shared src/fzf.c -o build/libfzf.dll
process_begin: CreateProcess(NULL, gcc -O3 -Wall -fpic -std=gnu99 -shared src/fzf.c -o build/libfzf.dll, ...) failed.
make (e=2): The system cannot find the file specified.
make: *** [Makefile:24: build/libfzf.dll] Error 2

I am somewhat of a newbie when it comes to make, but it looks like this change fixed it (lines 2-5 in Makefile):

 ifeq ($(OS),Windows_NT)
-    CC = gcc
+    ifndef CC
+        CC = gcc
+    endif
     TARGET := libfzf.dll