build: Remove spaces from variable-printing rules

This simplifies parsing when using these rules from scripts.

Makefile.am

@@ -4,7 +4,7 @@
 
 # Pattern rule to print variables, e.g. make print-top_srcdir
 print-%:
-	@echo '$*' = '$($*)'
+	@echo '$*'='$($*)'
 
 ACLOCAL_AMFLAGS = -I build-aux/m4
 SUBDIRS = src

contrib/guix/guix-build

@@ -119,7 +119,7 @@ fi
 for host in $HOSTS; do
     case "$host" in
         *darwin*)
-            OSX_SDK="$(make -C "${PWD}/depends" --no-print-directory HOST="$host" print-OSX_SDK | sed 's@^[^=]\+=[[:space:]]\+@@g')"
+            OSX_SDK="$(make -C "${PWD}/depends" --no-print-directory HOST="$host" print-OSX_SDK | sed 's@^[^=]\+=@@g')"
             if [ -e "$OSX_SDK" ]; then
                 echo "Found macOS SDK at '${OSX_SDK}', using..."
             else

depends/Makefile

@@ -2,7 +2,7 @@
 
 # Pattern rule to print variables, e.g. make print-top_srcdir
 print-%:
-	@echo '$*' = '$($*)'
+	@echo '$*'='$($*)'
 
 # When invoking a sub-make, keep only the command line variable definitions
 # matching the pattern in the filter function.

src/Makefile.am

@@ -4,7 +4,7 @@
 
 # Pattern rule to print variables, e.g. make print-top_srcdir
 print-%:
-	@echo '$*' = '$($*)'
+	@echo '$*'='$($*)'
 
 DIST_SUBDIRS = secp256k1 univalue