[MACTCL] Bug with tcl configure command - wrong compiler used

[G 3 <pro...@gm...>]

When I specified gcc-5 to compile Tcl, the Apple supplied gcc is used  
instead.

How to reproduce this problem:

cd to the Tcl8.6.6 folder
./configure --enable-framework=on CC=gcc-5
make

What I noticed:

When I ran the 'make' command, I saw this line in another configure  
output that ran:
"checking for gcc... gcc"

It said this for the above configure command:

checking for gcc... gcc-5

It looks like during the 'make' phase, the right gcc version to use  
is forgotten.

Note: running "CC=gcc-5 ./configure --enable-framework=on" does not  
help.