Remove COMPILER from Makefile

The same functionality is available by using COMPCXX and having another variable which does the same is just confusing.
There was only one mention on Stockfish Wiki about this which has been changed to COMPCXX.

closes https://github.com/official-stockfish/Stockfish/pull/5154

No functional change

.github/workflows/arm_compilation.yml

@@ -10,7 +10,7 @@ jobs:
     name: ${{ matrix.config.name }} ${{ matrix.binaries }}
     runs-on: ${{ matrix.config.os }}
     env:
-      COMPILER: ${{ matrix.config.compiler }}
+      COMPCXX: ${{ matrix.config.compiler }}
       COMP: ${{ matrix.config.comp }}
       EMU: ${{ matrix.config.emu }}
       EXT: ${{ matrix.config.ext }}
@@ -62,7 +62,7 @@ jobs:
           if [ $COMP == ndk ]; then
             export PATH=${{ env.ANDROID_NDK_BIN }}:$PATH
           fi
-          $COMPILER -v
+          $COMPCXX -v
 
       - name: Test help target
         run: make help

.github/workflows/compilation.yml

@@ -10,7 +10,7 @@ jobs:
     name: ${{ matrix.config.name }} ${{ matrix.binaries }}
     runs-on: ${{ matrix.config.os }}
     env:
-      COMPILER: ${{ matrix.config.compiler }}
+      COMPCXX: ${{ matrix.config.compiler }}
       COMP: ${{ matrix.config.comp }}
       EXT: ${{ matrix.config.ext }}
       NAME: ${{ matrix.config.simple_name }}
@@ -50,7 +50,7 @@ jobs:
         run: make net
 
       - name: Check compiler
-        run: $COMPILER -v
+        run: $COMPCXX -v
 
       - name: Test help target
         run: make help
@@ -59,7 +59,7 @@ jobs:
         run: git --version
 
       - name: Check compiler
-        run: $COMPILER -v
+        run: $COMPCXX -v
 
       - name: Show g++ cpu info
         if: runner.os != 'macOS'

.github/workflows/sanitizers.yml

@@ -6,7 +6,7 @@ jobs:
     name: ${{ matrix.sanitizers.name }}
     runs-on: ${{ matrix.config.os }}
     env:
-      COMPILER: ${{ matrix.config.compiler }}
+      COMPCXX: ${{ matrix.config.compiler }}
       COMP: ${{ matrix.config.comp }}
       CXXFLAGS: "-Werror"
     strategy:
@@ -47,7 +47,7 @@ jobs:
         run: make net
 
       - name: Check compiler
-        run: $COMPILER -v
+        run: $COMPCXX -v
 
       - name: Test help target
         run: make help

.github/workflows/tests.yml

@@ -6,7 +6,7 @@ jobs:
     name: ${{ matrix.config.name }}
     runs-on: ${{ matrix.config.os }}
     env:
-      COMPILER: ${{ matrix.config.compiler }}
+      COMPCXX: ${{ matrix.config.compiler }}
       COMP: ${{ matrix.config.comp }}
       CXXFLAGS: "-Werror"
     strategy:
@@ -172,9 +172,9 @@ jobs:
             if [ $COMP == ndk ]; then
               export PATH=${{ env.ANDROID_NDK_BIN }}:$PATH
             fi
-            $COMPILER -v
+            $COMPCXX -v
           else
-            echo "$COMPILER -v" > script.sh
+            echo "$COMPCXX -v" > script.sh
             docker run --rm --platform ${{ matrix.config.platform }} -v ${{ github.workspace }}/src:/app sf_builder
           fi
 

.github/workflows/upload_binaries.yml

@@ -11,7 +11,7 @@ jobs:
     name: ${{ matrix.config.name }} ${{ matrix.binaries }}
     runs-on: ${{ matrix.config.os }}
     env:
-      COMPILER: ${{ matrix.config.compiler }}
+      COMPCXX: ${{ matrix.config.compiler }}
       COMP: ${{ matrix.config.comp }}
       EXT: ${{ matrix.config.ext }}
       NAME: ${{ matrix.config.simple_name }}

src/Makefile

@@ -546,11 +546,6 @@ else
 	endif
 endif
 
-### Travis CI script uses COMPILER to overwrite CXX
-ifdef COMPILER
-	COMPCXX=$(COMPILER)
-endif
-
 ### Allow overwriting CXX from command line
 ifdef COMPCXX
 	CXX=$(COMPCXX)