Fix building instruction wrt make/gmake

Revert building instruction to mention the use of make instead of gmake
but add a note to tell FreeBSD and OSX users to use gmake instead of
make.

README

@@ -30,10 +30,12 @@ Documentation:
 
 1) Installation on a i386/x86_64/arm Linux/OSX/FreeBSD host (for Windows read tcc-win32.txt)
 
+Note: For OSX and FreeBSD, gmake should be used instead of make.
+
    ./configure
-   gmake
-   gmake test
-   gmake install
+   make
+   make test
+   make install
 
 Alternatively, out-of-tree builds are supported: you may use different
 directories to hold build objects, kept separate from your source tree:
@@ -41,9 +43,9 @@ directories to hold build objects, kept separate from your source tree:
    mkdir _build
    cd _build
    ../configure
-   gmake
-   gmake test
-   gmake install
+   make
+   make test
+   make install
 
 Texi2html must be installed to compile the doc. 
 By default, tcc is installed in /usr/local/bin.