Update htslib and add libcurl variant (#14504)

* Update htslib and add libcurl variant

This PR updates htslib to version 1.10.2 and adds a libcurl variant. The
libcurl variant defaults to True because, while it is optional, it is
highly recommended by the project developers.

Other things done:

- be consistent with quotes

* Change version in variant description

Apparently, `spack info` does not like the `@` character in a variant
description.

```
==> Error: Incomplete color format: '@' in
@1.3:.
```

var/spack/repos/builtin/packages/htslib/package.py

@@ -10,7 +10,9 @@ class Htslib(AutotoolsPackage):
     """C library for high-throughput sequencing data formats."""
 
     homepage = "https://github.com/samtools/htslib"
+    url = "https://github.com/samtools/htslib/releases/download/1.10.2/htslib-1.10.2.tar.bz2"
 
+    version('1.10.2', sha256='e3b543de2f71723830a1e0472cf5489ec27d0fbeb46b1103e14a11b7177d1939')
     version('1.9', sha256='e04b877057e8b3b8425d957f057b42f0e8509173621d3eccaedd0da607d9929a')
     version('1.8', sha256='c0ef1eec954a98cc708e9f99f6037db85db45670b52b6ab37abcc89b6c057ca1')
     version('1.7', sha256='be3d4e25c256acdd41bebb8a7ad55e89bb18e2fc7fc336124b1e2c82ae8886c6')
@@ -20,9 +22,15 @@ class Htslib(AutotoolsPackage):
     version('1.3.1', sha256='49d53a2395b8cef7d1d11270a09de888df8ba06f70fe68282e8235ee04124ae6')
     version('1.2', sha256='125c01421d5131afb4c3fd2bc9c7da6f4f1cd9ab5fc285c076080b9aca24bffc')
 
+    variant('libcurl',
+            default=True,
+            description='Enable libcurl-based support for http/https/etc URLs,'
+            ' for versions >= 1.3. This also enables S3 and GCS support.')
+
     depends_on('zlib')
-    depends_on('bzip2', when="@1.4:")
+    depends_on('bzip2', when='@1.4:')
-    depends_on('xz', when="@1.4:")
+    depends_on('xz', when='@1.4:')
+    depends_on('curl', when='@1.3:+libcurl')
 
     depends_on('m4', when="@1.2")
     depends_on('autoconf', when="@1.2")
@@ -37,3 +45,12 @@ def url_for_version(self, version):
         else:
             url = "https://github.com/samtools/htslib/releases/download/{0}/htslib-{0}.tar.bz2"
             return url.format(version.dotted)
+
+    def configure_args(self):
+        spec = self.spec
+        args = []
+
+        if spec.satisfies('@1.3:'):
+            args.extend(self.enable_or_disable('libcurl'))
+
+        return args