git: Fix various issues in the INSTALL guide (#800)

dist/compiling/macos.md

@@ -0,0 +1,32 @@
+### Compiling ImHex on macOS
+
+On macOS, ImHex is built through regular GCC and AppleClang.
+
+1. Clone the repo using `git clone https://github.com/WerWolv/ImHex --recurse-submodules`
+2. Install all the dependencies using `brew bundle --no-lock --file dist/Brewfile`
+3. Build ImHex itself using the following commands:
+```sh
+cd ImHex
+mkdir -p build
+cd build
+CC=$(brew --prefix gcc@12)/bin/gcc-12     \
+CXX=$(brew --prefix gcc@12)/bin/g++-12    \
+OBJC=$(brew --prefix llvm)/bin/clang      \
+OBJCXX=$(brew --prefix llvm)/bin/clang++  \
+PKG_CONFIG_PATH="$(brew --prefix openssl)/lib/pkgconfig":"$(brew --prefix)/lib/pkgconfig" \
+MACOSX_DEPLOYMENT_TARGET="10.15"          \
+cmake                                     \
+  -DCMAKE_BUILD_TYPE=Release              \
+  -DCREATE_BUNDLE=ON                      \
+  -DCREATE_PACKAGE=ON                     \
+  -DCMAKE_C_COMPILER_LAUNCHER=ccache      \
+  -DCMAKE_CXX_COMPILER_LAUNCHER=ccache    \
+  -DCMAKE_OBJC_COMPILER_LAUNCHER=ccache   \
+  -DCMAKE_OBJCXX_COMPILER_LAUNCHER=ccache \
+  ..
+make -j4 package
+```
+
+If the build fails while trying to find the macOS libraries, make sure you have
+Xcode installed with `xcode-select --install`. Homebrew will also help get the
+most recent SDK installed and configured with `brew doctor`.