Merge #14647: build: Remove illegal spacing in darwin.mk

63c74d2 build: Remove illegal spacing in darwin.mk (Jon Layton)

Pull request description:

  MacOS 10.13.6, `make -v` = `GNU Make 4.2.1  Built for x86_64-apple-darwin17.7.0`

  ```
  cd depends
  make HOST=x86_64-apple-darwin17.7.0
  ```
  Results in error:
  ```
  builders/darwin.mk:1: *** empty variable name.  Stop.
  ```

  This seems to fix it.

Tree-SHA512: 3481b9418571186c123942dc95b12bcaf47acbe2099ddd4524f5bb9dfe203175d7252bb7a1aa8ca5fec82578beeacfa06299472cb9d0d627c61f09486d74756c

depends/builders/darwin.mk

@@ -1,13 +1,13 @@
-build_darwin_CC: = $(shell xcrun -f clang)
-build_darwin_CXX: = $(shell xcrun -f clang++)
-build_darwin_AR: = $(shell xcrun -f ar)
-build_darwin_RANLIB: = $(shell xcrun -f ranlib)
-build_darwin_STRIP: = $(shell xcrun -f strip)
-build_darwin_OTOOL: = $(shell xcrun -f otool)
-build_darwin_NM: = $(shell xcrun -f nm)
+build_darwin_CC:=$(shell xcrun -f clang)
+build_darwin_CXX:=$(shell xcrun -f clang++)
+build_darwin_AR:=$(shell xcrun -f ar)
+build_darwin_RANLIB:=$(shell xcrun -f ranlib)
+build_darwin_STRIP:=$(shell xcrun -f strip)
+build_darwin_OTOOL:=$(shell xcrun -f otool)
+build_darwin_NM:=$(shell xcrun -f nm)
 build_darwin_INSTALL_NAME_TOOL:=$(shell xcrun -f install_name_tool)
-build_darwin_SHA256SUM = shasum -a 256
-build_darwin_DOWNLOAD = curl --location --fail --connect-timeout $(DOWNLOAD_CONNECT_TIMEOUT) --retry $(DOWNLOAD_RETRIES) -o
+build_darwin_SHA256SUM=shasum -a 256
+build_darwin_DOWNLOAD=curl --location --fail --connect-timeout $(DOWNLOAD_CONNECT_TIMEOUT) --retry $(DOWNLOAD_RETRIES) -o
 
 #darwin host on darwin builder. overrides darwin host preferences.
 darwin_CC=$(shell xcrun -f clang) -mmacosx-version-min=$(OSX_MIN_VERSION)