Remove gcc and g++ from Alpine image

[franz-josef-kaiser]

Both libraries add a lot of unnecessary bloat image size wise. From looking at what packages have >10MB in size, those are the most "heavy" packages while being just a dependency needed during build time.

apk info -a \
    | uniq -u \
    | xargs -r apk info -s \
    | awk '/[\w\d\-\.]*[[:space:]]installed[[:space:]]size\:/{name=$1;next} /^[0-9]+$/{size=$1} { if ( 10 < (size / 1024 / 1024) ) printf " %2.0f MB | %s\n", ( size / 1024 / 1024 ), name }' \
    | sort -u

which results in the following list:

 11 MB | musl-dev-1.1.12-r2
 28 MB | icu-libs-56.1-r0
 43 MB | perl-5.22.1-r0
 62 MB | gcc-5.3.0-r0
 66 MB | g++-5.3.0-r0

The package currently has 343 MB according to ImageLayers.io for Alpine PHP FPM 5.6. Removing those two only, would save 131 MB … or 1/3rd of the size. Everyone can easily add (and again remove) those build-only dependencies in images if using this one as base image. And "just for convenience" does not justify the size.

[franz-josef-kaiser]

Just realized that this is already addressed in PR #206